My nearly 18m old DD is very possessive of her toys. When friends children come over, she has an absolute meltdown if they touch any of her toys. Today, she went to another toddlers house with my DH, and he said she was an angel and very happy playing, but then in the afternoon when they came to us, she cried every time he touched anything of hers. I tried to tell her about sharing but I'm not sure she has any understanding at all. To be honest, we felt quite embarrassed! I feel like she's so different now, I'm not sure I know her at the moment.
Is there anything we can do to support her with learning to share?