I'd never tolerate being bullied by anyone - which is, essentially, what the son is doing.
I'd say that I might be free one day a month, perhaps, but certainly not every week. I dislike regular arrangements anyway, so they'd have to ask a few days before.
It'd be such a shame if precious time with a grandchild became a chore to be dreaded!
How to Keep Living at Home Longer
When a political leader lies on their CV - can you trust them?

