First Mom's Husband; How would you handle this?

Your maternal instincts are practically screaming at you, so you need to pay attention. If this man is giving you creepy vibes, then there is probably a very viable reason. Ultimately the only person who matters in this situation is your daughter and she is telling you in every way that she can that this man scares her. I would wait to bring up the overnight situation until they moved closer. If they do, do NOT silence that voice in your head in favour of sparing your child's first mom and her husband's feelings. It isn't about them. You are the child's mother and you know best. If you believe something is off about him, then you could be right. If there are to be overnights then the first mom can spend the night at your home or she can spend the night at her first mom's only when her husband is away. Again, it is not about sparing adult feelings, but rather doing what is in your daughter's best interests. Good luck!