Large items of furniture are, again, a different issue. It wouldn't be practical to go swapping such things about would it?
You are not talking about other items, so "what if she wants my curtains" type comments aren't really relevant. You are talking about a picture frame, so that is what my comments are all based on. One easily moved item, which is in fact one of eight.
I am in the situation that myself & my siblings each have certain things from our parents' house. Some old things passed down through generations, some newer things that either mum or dad bought.
If one of us had eight picture frames & another wanted one of them, then I'm 99.9% certain any one of us would hand it over. We definitely would then also say "could I have one of mum's Swarovski pots please?" IF we did actually want one. Not just as a tit for tat request mind you.
We've split up sets of things. If you've got them because they have sentimental value, having belonged to your mum, it hardly matters that your sibling has some of the set too. It's not Antiques Roadshow, you don't need the complete set in one place.
I've only really got on with my siblings since our parents died. We have nothing in common (except parents of course) and would also not be friends if we weren't related. We meet up a couple of times a year.
You've made your mind up as, having read lots of opinions, you are still going to do exactly what you originally intended to do in the OP. I hope your sister is happy with the small frames (as that's all she seems to be getting).