Hello @LemonadeFlashbang,
I’d suggest you use a storage object to keep track of the taken names and keep this record updated as matches are created or terminated, reading it to check whether a name is available or not.
You can create an authoritative match handler by setting up a custom RPC that calls the runtime matchCreate API, provided you also implement the related custom match handler hooks. To make it relayed, you’d simply add logic to relay the messages to all presences within matchLoop. You can see an example of an authoritative match handler here, it should be easy to infer how to strip out all the authoritative logic to transform it into a relayed match handler.
Authoritative matches don’t support using names though, so you’d have to implement something as described here: Custom matchId for private lobby/room? - #3 by mharis.
Hope this helps.