Need help with a filter problem

Not automatically, but you could set it up so that users could add/remove themselves from projects - which is what you want, yes?

You won’t find anything in the Glide docs about trebuchet, as it’s an advanced technique developed by a couple of our community heroes - @Robert_Petitto & @Lucas_Pires. It takes a bit to get your head around it, but if you’re willing to learn then it opens a lot of doors.

Watch this video for a good introduction:

And there are one or two other tutorials available, you’ll find those by searching.