Surely your nanny is cooking the children their evening meal if they are that young? And then essentially you get home and put them to bed? It's what we've always done with three kids (enormous apologies for not having four, btw, I hadn't realized an extra child made that much difference - it doesn't seem to when ours have a friend over) if we were working full time.
Find a nanny that makes your life easier - not sure what yours is doing if she doesn't manage to feed the kids for you?
I get that you are busy. Sure. It is busy with two of you working ft, and loads of kids, and at least one dog. But that's life. And having emigrated, well, having visitors is life too. You just have to suck it up and work out how to fit it in.
Your sudden dislike for your mil since she refused to move out there with you is colouring your view. If this was a dear friend or your own mother wanting to come and stay for a month, would you be more accommodating? None of us can choose our relatives.
But, whatever, I assumed you already had PR given your feelings about your mil's decision not to move, tbh. Hope it works out how you want. The first year is always interesting - we paid our mortgage late three times. We're just about organized, though. Still in a 2 bed condo with 5 of us (and the visitors
) but unless we win lotto 649 we can't afford to move.
Just tell dh you are cutting off all ties with mil because she won't do exactly as you want. Job done.