I really like both
Gregor and
Dougal, and both sound good with the mn and with your other kids' names, imo. I think
Enid is too similar to
Eli, personally, and
Ivy too close to
Iris, too. :-/
Some suggestion for Scottish boys' names:
TavishGus (maybe as a nn for
Fergus?)- would fit in perfectly with his siblings, I think :)
FraserMunroKerr