I am developing API's for chat application that has one-to-one and group chat based on invite. e.g I want to chat with someone first message that i am gonna send him will go as a invite after accepting invitation they can chat and add other users in chat [Group chat]. I am little conscious about minimum tables. The database that i am using now is not fulfilling my needs. Here is image that shows my current DB.
Suggest me some changes or any other options.
Thanks