I can't see how you can make long term custody plans anyway.
There's two people whose voices need to be heard in this.
In a few years there own wants and wishes need to be taken into account.
In five years time when they become more independent they might have things they want to do. Take up activities, see their friends . It shouldn't be set in stone at this stage but should be fluid enough to accommodate the wishes of your children.
At 11 I would have been very upset to be told what I was doing, where I was going on a Saturday for example.
I had a lovely nana and one I wasn't keen on even at a tender age. On the rare occasions I had to be looked after by the one I wasn't keen on I hated it. I hated her creepy house. Thankfully it wasn't every weekend. I think there would have been a few tantrums from me if it had been
I would make sure any contact arrangements have your children's wishes taken into account.
You are doing so right thinking ahead for them now and fighting for them.
My grandchildren ( the he ones aged 12, 9 and 6 ) had a day in yesterday. I've been away for 2 weeks and said to my daughter aw, you should have brought them round to see me (she takes them here, there and everywhere doing interesting stuff, ) to which she replied that she didn't think she could get them out of the house. So be prepared for all of that and try to build that into any future contact plans. I'm sure you will.
You're bonnet and you're onit ;-)