What should i do? ( please read this u will be giving much needed advice to a very special girl)

Ok so heres the big deal here my little sister is in 4th grade she is currently 9 she will be 10 on december,28 and she has a little crush on her boy best friend :P so anyway i know shes a little to young to have a boyfriend but they can always stay with each other at warrendale till 8th grade cuz they only go up to 8th then he can tell her his high school and she can go there and they can live a life togetha but anyway without further ado and all these words i will get to the point SHE ASKED ME FOR ADVISE TODAY AND I WAS LIKE UH ERR UM AND NOW IM ASKING U FOR ADVICE TO TELL HER PLZ!plz answer this question oh so u can answer is i also should tell u this ok so on wensday she said he was acting all shy and using hand language to talk to her but today he finally spoke up she thinks he was giving her love looks ( her way of saying when a boy is to shy to talk to u cuz they like u ) anyway so i think he was to i think he was shy so he might have a little crush and her too but she really wants this to happen THANK U! ( I think she should tell him since he likes her back what da u think?!)