I agree with Davide. By withholding the kids you are guaranteeing the situation will be worse. You would be giving your wife the ultimatum - do what I say or else you won’t have the children. That is controlling. Yes her taking the children wasn’t fair on you but that is done now. You don’t even know if she has received the letter from your solicitor. Maybe check with the solicitor when it was posted out.

How do you know her parents do nearly all the childcare? You aren’t there. What basic home comforts are they missing out on?

You say you wish to have the children on school days and you wife then weekends? Why cannot it be split equally? Surely that would be the starting point? You must want some weekends with the children yourself? So if she doesn’t agree with your plan tomorrow you will refuse her access to the children until it goes to court?

You need to separate your role as a parent and your relationship with W. Don’t put the children through horrible battles - they will know and be aware.

M: 17 T:17 Me:42 H:48
BD 23/12/2017 H says ‘I don’t want to be married’
D 17 D 15, D 13, S 10, S 10