This is something I thought about a lot because I remember it as a problem from my own childhood (that is, I remember being very upset at being pushed into giving things up that I still tremendously valued, even if I didn't play with them much). What's working for us is to take DS's feelings very seriously, and not push him to give things away if he's not ready to - I think that can easily backfire, and in the end, it doesn't make so much difference if something gets given away this year or next; if it's not being played with much in the meantime it's in just as good condition next year and will eventually get played with for the same number of years in total, probably! It has to be his decision that he's outgrown something, not mine. The most important thing at this stage is to help him feel safe giving things up when he is ready, rather than hoarding for no reason. I also offer the option of keeping treasures that he's outgrown "for his children" (helpfully, we don't have the space to do that with a lot of things, but it means he isn't absolutely stuck knowing he's outgrown something but not feeling able to give it up).
I don't think I started this until DS was 4, though, and I think it might have been harder or even impossible when he was a toddler. I'd suggest:
- not expecting to get rid of half her stuff in one go!
- planning what you'll say when she *is* willing to give something up that *you* value and want kept!
