I approved this but by default multiple values for a param mean OR, not AND, and the & symbol is already used in the DQA. What we would need to do is probably create a new param, eg ident_users_ids, that uses AND for multiple values.
why would it be useful to know which observations you and a friend have both identified? are you working on curating things together? roughly how many observations have you and your friend identified? a handful? hundreds? thousands? tens of thousands?
i’m asking questions here to try to get you to elaborate on what the problem is that you’re trying to solve. you’ve described a solution – really more than one solution since you’ve talked about both inclusion and exclusion filters – and it’s not clear to me why either solution is desirable or whether they will actually solve your particular problem or whether the problem already has a solution (because i have no clear idea what the problem is).