I don't like Greyson, but RichardJames is nice.Normally, I don't like two nouns in a combination. But I must admit that HollyWinterJane is very attractive. It must be Jane in there that keeps it name-y.
I don't really think they go well as a sibset... James, Richard, Jane, and Holly sound like they go together, as do Winter and Greyson (maybe not go together, but I can see them as a sibset).