Best Practice question to handle Friends

Hi !
I got a question regarding our use case of handling comet chat user to discuss between them.
On our App, (using our Ui Kit) we want only people that known each other to be able to discuss between them.
So we don’t have a list of all users on our plateform where you can start talking to anyone.

What we did is when a user is introduce to another we put them as friend on cometchat. And we list only friends people.

Our interrogation is about the ability for a tierce person (register on our app) to chat with someone that he is not friend with. Let’s say he knows/guess his Uid, he would be able to chat with him. And we don’t want that.
I understood that you don’t on cometchat backend check if someone is trying to chat with a non friend.

So I have 2 questions for you please :
1 - Do you plan to have like a configuration that if we are full “onlyfriend”, if someone is trying to start discussion with a non friend it block or return something ?
2 - Do you have advice to handle this kind of setup/ user case ? And avoid someone cunning find a way to start conversation with anyone if he has it’s Uid ?

Thanks a lot for your help and advices.