Such an upsetting situation to be in Panda, you have my heartfelt sympathy.
My overall feeling having read your post is that you need to stand up for yourself with your D, your s.i.l. and your H. Doing so may not necessarily improve the situation but could go along way to enabling you to deal with what's happening.
My answer to your question as to what more you can do for your D to want you in her life is I'm afraid, nothing. There's a huge difference between someone wanting you in their life because of the relationship they have with you, and wanting you because of what you do for them.
From what you've posted it seems that your D is using the love you have for your GC as a stick to beat you with. No contact for 3 years after you looked after the children so they could have their honeymoon, and now, it's OK for you to look after your GC but your s.i.l. wont have you in the house.
We've been estranged from our youngest son and only GC for 7 years so I totally understand your fear that if you don't do what your D and your s.i.l. want, they may stop you from seeing them altogether. They've done it before so who is to say they wont do it again.
Your D and s.i.l. know that this unspoken threat hangs over you and they are using it to their advantage.
IMO your D wasn't annoyed that you picked a side, she was annoyed that you didn't pick her side. Any parent would have done what you did, and try to smooth things over between 2 of their AC especially when one was going to be banned from the other's wedding. You D's response was childish and cruel.
I agree with Starlady with regard to having the children in your home. It's your home too and he's out of order saying you can't have your GC there.
Lesley's advice is spot on here, put precious things away when they're coming so there's no possibility of them being broken.
As for your s.i.l., has he given any reason for you not being welcome? If this goes back to the incident between your D's and your attempt to resolve the matter then he has a cheek IMO, having had you look after the children so he could enjoy his honeymoon. If that is the reason, then he should be man enough to say so or to say what his reasons are.
I do understand you not wanting to lose contact with your GC. My heart goes out to you and all GP's who lose their GC that they've known and loved. We're fortunate that we never knew ours so in that sense it has been easier for us.
Perhaps you should think about reducing the amount of time you spend looking after the children. I realise this carries the real risk that your D will be annoyed and you'll be estranged again and only you can decide whether or not the way you're being treated, "taking crap", feeling at the end of your tether and feeling "anxious all the time" is something you can sustain long term.
I hope you can get something resolved, if only that's having your GC in your own home to relieve some of the financial and practical pressures of seeing them.
