I'm just going to give you my story to make you have a little think about that childcare offer.
My lovely Mum lived very close to sister and provided her with massive amounts of childcare, all agreed, everyone happy. She had been providing this childcare since my nephew was 10 weeks old. He is now 15.
She was a spritely 62, active, and relatively healthy, no issues. She underwent a routine mammogram and was diagnosed with breast cancer. They MRI scanned her and she lit up like a Christmas tree. The cancer was everywhere in her body; brain, legs, bones, chest, lymph nodes etc
They decided to give her chemo even though she was terminal because she had no symptoms of anything. 10 weeks later she was dead. Devastated does not even come close to how we all felt and still feel 4 years on.
My Dad is still alive and has taken over the childcare although clearly at the ages my niece and nephew are it is not really childcare. They are 15 and 11.
My MIL is 63 and is currently undergoing chemo. She again is active, very healthy in terms of exercise and diet. Just had a bad back one day, turns out to be leukaemia. Very aggressive. This wasn't the retirement she had planned. We are 5 months into treatment.
So the whole point of this is, if anything happened to your Mum could you still work and afford the house you want to move to? You need to allow for childcare should you need it.
I am not saying don't sell to your Mum, because quite frankly I would.