Baby won’t sleep in crib!

So my baby boy is about to be 1 month, and my in-laws got to town Wednesday and have been wanting to hold him 24/7(they love 23hrs away) so I understand why they would want to. But they have been holding him so much that he falls asleep in their arms and then he doesn’t want to sleep in his crib at all! So today we kind of limited how much they held him and thought it would help tonight but so far he still doesn’t want to sleep in his crib. Just arms. Lol. So any tips to help get him back to wanting to sleep in his crib and not peoples arms!?