I agree with v. Some more opinions from social workers and people that work with kids perhaps, before you uproot them.
I would live in a card board box to be near my son. Her actions are not normal. Not sure why you want to go put of your way and the kids way to make things easier for her. I know you say its for the kids benefit to be nearer to her. But shes the adult. And had and has choices But im not a professional that works with children.
I will tell you my MIL went out of her way to shield my ex from what his dad did. Kept telling him his dad was out providing when really he had left. When he came back she denied and lied aboit what was obvious. I feel that the secrecy and enablement regarding bad behavior and marital committment contribited to issues. Because of this i have been forthright with my son. And will continie to be when he gets older. I will not cover up for his bad behavior.