I don't really like names in a sib-set to not flow. I know a sibset that is L!nley, F@ith, Ell3ry, and @bel. L!nley, Ell3ry, and @bel are almost unheard-of, while F@ith is fairly common. Oh well. Here's the ones I think would flow best:
Lily, Chase, Zack, and Eden
Lily, Chase, Zack, and Chloe (although there is a TV show about twins named Zack and Cody, so I'd be wary of that, since Chloe sounds similar to Cody)
Lily, Chase, Zack, and Shiloh
Lily, Chase, Zack, and Isla
Lily, Chase, Zack, and Brody (Again, with the TV show.)
Lily, Chase, Zack, and Jude
Lily, Chase, Zack, and Finn
Personally, I think Riley and Chloe, Kendall, Austin all fit with your other children's names
Yeah, people might ask if one of your kids is adopted. lol.
Originally Posted by kala_way
Actually as a kid it was really important to me that my name fit in with the rest of my family - and I don't have siblings.
I was always an outsider and a loner as a kid, knowing that my family at least thought I fit and belonged even though in very many ways I was nothing like any of them. This doesn't mean each name needs the same number of letters, and has to start and end with the same letter and have the same origin. But some cohesion as Kala_Way suggested would be really important to me.
I think since you are thinking about keeping shorter names that have no nn's that completely qualifies as cohesion of sorts.