Let the girls make their own minds up.
If she has a sleepover and isn't impressed she is probably not someone your DD wants to be around.
Another point to make is, if this super-rich family have any moral values they will be bringing their DD up to be polite and accepting of others.
I've worked for wealthy families, lived in some amazing houses, but, tend to find the kids get driven everywhere, not allowed to play with the children in the same street "because the parents are jealous as our house is the biggest in the street" BS I say.
If this child wants to come for a sleepover with your DD then great 
My friend who i've known since childhood still struggles, but, her door is always open and she would give you her last slice of bread to help you out that's just the type of person she is. Has nothing material, but, great values and that's more important.