Question regarding Chinese honorifics

[firestar]

I'm looking for two things, really: a) how people would refer to a child that is not their own (google tells me it would be Xiao *name*, but I'd appreciate some confirmation on that) and b) ...okay, b is a bit long-winded. A character I'm writing for has been de-aged back to about 9 years old and doesn't remember anyone, so he's now tacking jie and ge onto everyone's names; however one of the other characters is exclusively called Xiao Qiao and I don't think Xiao Qiao Jie is... something that would work. Her name is Qiao Qian but she's never referred to that way so I'm a bit at a loss how to work this and google is not helping.

Language is Mandarin, not Cantonese, and it's fic for a Taiwanese drama; I'm not sure if there'd be much difference between Taiwan and the Mainland for this, but I'm mentioning it just in case there is.

Thanks in advance.