How do i collab with my family member? We wanted to be on the same project with different accounts, don't think it's possible though.

Currently its not possible.

You should be able to both work on the same computer, or continuously remix one project while adding things.

Well, you could try sharing an early version of the project so that the other person could add a part to it, then add code from their version of the project, although it could get tedious with some mistakes.

Another thing you could do is have different projects for different segments of it, like one project to have the art, one project to handle enemy AI, and another to handle menus.

There are also external browser extensions that let you do collaborations, although I wouldn't recommend using/mentioning them here since they're not officially created and could come with issues/insecurities.