Maybe Sean...any other ideas?

[Phteven]

I was going to say Oliver too. It seems to fit with your other boy's names.

Ruben
Angus
Edward
Alistair

[foreva*your*mummy]

I like Rhys ( my DS has this for his middle name, spelt like this aswell) and Arley I havent heard this before but really like it!!.
other names I like are Fletcher and Lawson