I think I agree that
Morrigan is too much for a first name. I don't like it, I just find the sound unpleasant. It kind of reminds me of porridge (the word, I mean). Also the
Morrigan is not the most charming mythological figure. I prefer
Morgane (or
Morgan I guess but that's more of a surname for me).
I would use something quite simple, to go with
Alexander and tone down
Morrigan. Like (sorry for any repeats, just take it as me seconding the suggestion):
Rose MorriganAlice MorriganEva MorriganLily MorriganKate MorriganBridget Morrigan /
BridieMary Morrigan Kathleen MorriganSophia MorriganClare MorriganEliza MorriganIsabel MorriganAdele MorriganCecily MorriganElinor MorriganSusan MorriganLydia MorriganEvelyn MorriganLucy MorriganRosalind MorriganRachel MorriganAbigail MorriganRebecca Morrigan