Yes I am wishing they'd stayed there!
To the pp who said stop uniting her round, I don't. Unfortunately she is still my dh's sister and my dc's aunt.
They are of sentimental value to dh, dh was the one who put them in the loft of his parents house when he lived there. He went travelling and cleared out his room getting rid of what he didn't want and storing what was special to him. Things change over the years and we me and moved I together. He hadn't forgotten about them, he knew they were there, however his parents weren't in a rush to get rid, life moves on, we had children, moved house 5 times in 6 years and didn't have space to store the things he'd packed away in his parents loft 10 years ago (which is what I meant by 'all but forgotten about them')
To the pp who said I was the only one with out a claim, I absolutely agree with you. I fully support my dh in whatever he wants to do with them, if he wants to sell, keep, bin whatever I'm happy with that. Dh doesn't have an account on mumsnet and I was asking on behalf of him.
In the op I said collection as that's what I was told, I asked him how many coins after a pp asked and that's when I found out there were only 3-4.
Dh has decided he doesn't want to sell the coins and actually wants to keep them as an investment/collection for the kids, he told sil this morning and tried to give back the coins she gave him. She refused, went home in a huff and said when we do sell she is entitled to 50%.
It'll blow over as she's constantly getting huffy over things like this and dh also wants to add to our will to ensure they get passed on to the children in the even of our death (he is legally traind and very practical, this was one of the first things he said after we shut the door!)
To the pp's who said pil should get something, they don't want anything. They think she is being incredibly selfish and rude and it's nothing to do with her.
And finally we know which coins are her because there are 2 of each type. Bil and sil liked to be the same (I mentioned they were twins) and ha to have everything similar, so there are a few coins (I haven't actually seen the coins in the collection btw) that are the same or similar so dh knows they came from bil and sil.
Thanks for all your help, I think we're going to put them away, continue adding to them when we see nice ones for the children and not mention it to her again. He tried to do the 'right' thing and she refused the actual coins.