...and as long as it makes sense to you, it sounds like a good idea. Just don't get yourself into enabling them. (BTDT, got the T-shirt). If things go bad, make other arrangements. Let them know up front that's the plan, and not to be offended if it happens. Also let them know that works both ways.
BTW, I think you neglected telling us about the new baby until now. Congratulations!
My DS is moving in with us this weekend for a few months. His lease is up and he thinks he is going to be transferred and will want to move again soon. I told him he didn't have to pay rent IF he took over the yard work AND used the windfall to pay off the engagement ring! (You know, the Wedding that Never Was. Still owes $1,900 on the ring. Thinks he can pay it off by August. Yes, he has learned a lesson here).