This has a couple other bits of information too with someone who attended the event

Post by @snowflaketale12 · 6 imagesTumblr

The post Disney China made was taken down and replaced with a vague synopsis that removes the leaks

I agree with that videos conclusion about who the mysterious family member could or couldn’t be. A lot of people are saying Anna and Kristoffs kid but there are several reasons that wouldn’t work. I do think the family member can’t be somone related to Iduna though, because her tribe was killed when she was a little child, then she was adopted by Yelanas tribe. It’s more likely to be Agnarrs mom, Rita, or perhaps a cousin of his.