IOS 12 iMessage unusable.

Just like everyone else on a single Apple ID, messages go to everyone or no one but certainly not to who they are supposed to go to. Called support they said it was supposed to be this way and that IOS 12 is fixing the issue that allowed text to previously work on a single ID. I have kids on my account, I am not making then apple IDs. I have seen articles that this is being identified as a wide spread issue. I can not get it to work correctly in SMS only either. Basically we can not text...This is an absolute deal breaker. Is it going to be fixed?