Do birds steal other birds' nests?

I’ve been observing two sterling jays (a mom and dad, I think) build a nest outside my front door for the past few days. All of a sudden a third one swooped in and scared them off today. Now, I’m not sure who it rightfully belongs to, but is it possible that he’s a squatter—a nest-stealer? Do birds do this?

Or maybe it’s a gay couple and a surrogate???