I like Declan out of all of the choices.
My favorite is Fraser for boys but I think Declan meshes better. (You already have two -er boys and on -n boy. For me Declan is a better balance.)
I really like Declan Stanley or Declan Arthur
Also while I love the Indy Summer suggestion above I keep thinking about the term Indian Summer when I read it. -> not necessarily a bad thing, just a thing. I have the same issues with Alaska Skye, just too descriptive for me.
I'd probably use Daisy as a FN for a girl. Daisy Jessica or Daisy Skye.
I would pick Declan personally!
Declan would probably be my first choice sound wise, but I like Fraser because of Shep choosing it and especially if it's after a place he used to camp, etc. That's a really nice association and name story for someone to have. Glenn is a perfectly good name, but I don't think it fits very well with your other kids!
I wouldn't choose Alaska as a name right now, just because of the sudden and extreme popularity of the book "Looking For Alaska", which will make the name seem incredibly trendy and probably dated in a few years. Juno/Juneau would be a cool alternative, though! And I think Indy goes better with your other children's names, as well.
I do definitely think both Declan and Owen are trendy, especially Owen. But if you don't care about that or popularity, then no worries! I love the nn Dex for Declan.
Fraser is pretty cool and unique! I don't think I've ever seen it mentioned on here! It's very special that Shep came up with it :)