I like Delia. It's distinctly feminine and I like to see a feminine middle name used when the first name is masculine or gender neutral. Felicity is another good choice. ETA: But I'm not sure if Felicity would sound right with your last name, similar endings.
I think in the mn slot I'm ok with the ie endings being the same. I like them all so I'm having a hard time rating. I had my family put them in order of favorite but all the votes aren't in. Thanks for the constructive feedback.
None of them seem to flow very well with Harlow for me but it might just be because Harlow is really NMS. Voted Harlow Felicity b/c I like Felicity better but I think Harlow Delaney flows the best.
Re: Girl MN
I also like Marilla from Anne of green gables.