Anyone can claim two casinos are sister sites. Proving it is the harder bit — and the only bit that matters when something actually goes wrong with an account, a withdrawal, or a self-exclusion you assumed had been applied.What most players don't realise is that the proof is already out there. Every connection between UK-licensed casino brands is documented in public registers. The UK Gambling Commission and Companies House together publish enough material to map almost any sister-site network in about ten minutes once you know what you're looking at. No subscription, no insider access, no scraping anything you shouldn't. Just two free government databases and the patience to read what's actually on them rather than what the casino's homepage would prefer you to take on trust.This is the method we use at Alterplay every day. Here it is, broken down so you can do it yourself.
What you're actually verifying
Before you start poking around in registers, it's worth being clear about what "sister site" even means. The term gets used loosely, which suits operators fine and helps players almost not at all. In practice it covers three quite different relationships, and the difference between them matters.
The tightest version is a shared licence. Two or more brands operating under the same UKGC operating licence, held by the same registered company. That means shared wallet infrastructure, shared compliance team, shared responsible-gambling systems. A self-exclusion at one of these brands should propagate automatically across all of them. Should being the operative word — we'll come back to that.
A looser version is shared parent. Two brands held under different UKGC licences, but ultimately owned by the same parent company. Operationally they're separate. Strategically and financially, they're not. Decisions about risk appetite, AML enforcement, and customer treatment all flow down from the same boardroom, even if the brand managers have never met.
The loosest version is shared platform, which most people would recognise as a white-label arrangement. The licensee supplies the technology, payment processing, and (usually) the licence itself to a third party that owns the brand. Same back-end, separate ownership. The licensee is the entity the Gambling Commission can hold responsible. The brand owner often controls little more than the colour scheme and the marketing copy.
Knowing which of these three you're looking at changes everything about what to expect from a network — bonus eligibility, exclusion handling, complaint escalation. The whole point of the verification process below is to tell them apart.
What to grab before you start
Open the casino site you want to check. Scroll all the way to the bottom of the homepage. You're after four things: the legal name of the company that operates the site, the UKGC operating licence number (usually five or six digits, sometimes followed by extra codes), the registered company address, and the domain name itself.
The licence number and operator name will almost always be sitting in the footer. The registered office address is more often tucked away inside the terms and conditions, sometimes uncomfortably far down. If any of these are missing, hidden, or made deliberately hard to find, you've already learned something useful. Every UK-licensed gambling site is required by Section 8 of the Licence Conditions and Codes of Practice to display its licensed status clearly. A site that doesn't is either negligent or doesn't have anything to display. Neither is a great sign.
Once you have those four data points written down somewhere, you're ready.
Step 1: the UKGC public register
The Gambling Commission keeps a public register of every licensed gambling business operating in Great Britain. As of June 2026 it lists 2,657 records, updated continuously. You can search it by business name, by trading name, by domain name, or by licence account number — whichever you happen to have to hand.
Type in the domain or the operator name you collected. The register comes back with a profile that looks dense at first glance but is actually fairly easy to read once you know what each field is doing.
You'll see an account number, which is the unique reference for the licence holder. The account name, which is the legal name of the company that actually holds the licence. A head office address. A licence status field that will read one of: Active, Expired, Forfeited, Lapsed, Pending, Revoked, Revoked (Non payment of fee), Surrendered, or Suspended. There will also be dates for when activity started and (if applicable) ended, a count of trading names and domain names the licensee has declared, and a regulatory actions field listing any sanctions or settlements the Commission has imposed.
First check: licence status. It needs to say Active. Anything else means the licensee is not in good standing, and the fact that the website is still humming away in the meantime doesn't change that. Depositing real money at a brand whose licence has been Revoked, Suspended, or Lapsed is the kind of decision that looks much worse in hindsight.
The single field that does the most heavy lifting for sister-site mapping, though, is Domain name status. This one has three possible values: Active, Inactive, or White label. That third value is the one you care about most. If the brand you're checking is flagged White label on the register, the licensee is supplying the platform — the brand itself is owned by somebody else, and the other domains on the same licence are not all corporate sisters in any meaningful sense. They're tenants.
If the domain is flagged Active rather than White label, the licensee is the direct operator. In that case, every other Active domain under the same account number is a genuine sister site — same operator, same licence, same compliance framework. Same complaints process, when it comes to that.
A practical tip: the entire register is downloadable as a CSV or Excel file. If you're checking more than a handful of brands, work with the spreadsheet rather than running searches one at a time. Filter by account number and the whole network appears in one view.
Step 2: Companies House
The UKGC register tells you who holds the licence. It does not tell you who owns the company that holds the licence. For that you want Companies House.
Take the legal name you got from the UKGC register, paste it into the Find and update company information service, and look at what comes back. The match should be more or less exact — UKGC licensees have to be registered legal entities in the UK, and the name on the gambling licence has to match the name registered at Companies House.
What you're looking at in the company profile: the registered office address (which should match the head office address from the UKGC, more or less), the date the company was incorporated, every current and resigned officer, the filing history (annual accounts, confirmation statements, name changes, any registered charges over the business), and — the important bit — the Persons with Significant Control register.
The PSC register names anyone who holds more than 25% of shares or voting rights, or who otherwise exercises significant control over the company. This is where real ownership lives. If the company on the UKGC licence is itself owned by another company, the PSC filing will name the parent. Search the parent and you can keep climbing until you reach the ultimate beneficial owner, which is usually a holding company somewhere recognisable.
This step is how you find shared-parent sister sites. Two completely different UK licensees, with two different UKGC account numbers and no overlapping brands at the gambling-register level, can turn out to be wholly-owned subsidiaries of the same parent company. From the UKGC's register alone, you'd never spot it. From the PSC filings, it's right there in plain text.
One thing to keep in your head while doing this: Companies House does not verify what's filed. The service records what companies submit. Most of it is accurate, because submitting false information is a criminal offence, but the registrar isn't fact-checking individual filings. So if a discrepancy turns up between what an operator says about itself on the website and what's in the Companies House record, the answer is to dig further, not to assume one or the other is automatically correct.
Step 3: audit what the site says about itself
You now have two sources you can lean on: the UKGC register and the Companies House file. Go back to the casino site and compare them against the disclosures the site is making.
Check that the legal name in the footer matches the account name on the UKGC register. Check that the licence number in the footer matches the account number. Check that the registered office address in the T&Cs matches the address on file at Companies House. Check that any company registration number cited on the site matches the Companies House record.
If all four match cleanly, the disclosure layer is in good shape. If anything doesn't, it might be innocent (recent change of name not yet rolled out across the site) or it might be a problem (deliberately stale information meant to make the operator harder to trace). Either way, find out which before you commit any money.
This part takes maybe thirty seconds once you've done it a couple of times. It's also the step almost no one bothers with, which is why operators occasionally run with misleading footers for months at a time without anyone noticing.
Step 4: keep an eye on it
The corporate structure behind a UK casino brand is not a fixed thing. Brands launch, get sold, migrate platforms, and lose licences with surprising regularity. A relationship you verified six months ago might no longer reflect what's actually true today.
If you're planning to use a brand seriously, there are two things worth setting up. The first is Companies House's free Follow function, which sends email alerts whenever a new filing is accepted against a company you've followed. Any change of officers, change of registered office, new accounts, or change of name will turn up in your inbox a day or two after it happens. The second is keeping half an eye on the UKGC's regulatory actions register and its public statements page, where enforcement actions, settlements, and licence suspensions are published. Major changes at a licensee almost always appear there before they appear anywhere else.
It's about as close to early warning as the public record gets.
What this looks like in practice
Imagine you've just signed up at a casino brand you've never used before. The footer says it's operated by Example Operations Limited under UKGC licence number 12345. The T&Cs name a registered office somewhere in central London. You want to know what else this operator runs.
Search Example Operations on the UKGC register. The profile comes back showing Active status, twelve trading names declared, eighteen Active domains, and four marked White label. Right there, you have your answer about the network shape. The eighteen Active domains are genuine sister sites — same operator, same compliance team. The four White-label domains are platform clients with separate brand ownership; they share the back-end with the others but are otherwise their own thing.
Now open Companies House and search the same legal name. The registered office matches the T&Cs. The PSC register names a parent holding company. Search the parent and it turns out to hold 100% of another UK gambling company with a separate UKGC licence — six more brands you wouldn't have found from the gambling register alone, run by different staff but ultimately answering to the same boardroom.
Last bit: footer audit. Licence number on the site matches the UKGC account number. Registered office on the site matches Companies House. No discrepancies. Everything clean.
You now have a clear map of the network: eighteen direct sister sites, four white-label tenants, and another six brands held under a separate licence by a sibling company under the same parent. Self-exclusion at the original brand should propagate across the direct eighteen automatically. The six shared-parent brands are a separate question — same owner, separate compliance team, no automatic propagation guaranteed.
Total time from start to finish: about ten minutes.
Where the public record gives up
This method gets you the corporate skeleton with high confidence. It will not, on its own, tell you absolutely everything.
What it won't tell you: the commercial terms of any white-label deal, which means you can't know from registers alone how much operational independence a white-label brand actually has. Which customer service vendor handles complaints across the network. Whether two brands share a payment processor. Whether their marketing teams are joined up. Those things require either looking at the site itself in technical detail or contacting the operator directly.
It also won't tell you whether self-exclusion has, in practice, propagated correctly across a particular network. The Commission requires propagation under SR Code Provision 3.5.5 of the LCCP, and the multi-operator GAMSTOP scheme is meant to catch the gaps. Implementation isn't always perfect. If you've self-excluded from one brand and you're worried about a sister site, do not rely on the registers — contact the operator and get written confirmation that the exclusion has been applied across the network. Public records will only take you so far when something specific is on the line.
That caveat aside, you'll have done more verification work in ten minutes than the vast majority of players ever do, and you'll know things about your operator that most players never will.