Oliver Matthew sounds great!!
Joshua Matthew also sounds nice.

I actually dont think Ash sounds good with any of these names.

Girls: middle name will be Elsie
Lila is lovely. I would spell it that way as it looks neater and classier. Lila Elsie is sweet.
Thanks Mumtobe I like the sound of Matthew as a middle name too (it's my maiden name, sort of) but Ash is DH's initials. I think he'd be happy with either though.

That spelling of Lila is really cute - thanks for the tip!