I l
ve Eleni, really pretty and a bit different. Along similar lines I also like Helena with Lena as a shortening
We've got a Megan, and Eli would have been Thea if he'd been a girl. Obviously that's very similar to Theo (M would have been a Theo, but H went off the name when I was pregnant again) - I don't know whether that's too much, or might be a nice way of remembering Theo for you?
I wonder whether we should have gone more biblical with M (especially having given E such a biblical name) but I'm not sure what we'd have gone for - maybe Anna (with poss Anya as a 'shortening') or Talia. I also love Orla and Emma (maybe short for Emmeline)