It really should be my favourite way to play too but for some reason I'm all obsessed about stats, skills and classes for the various future children that I'm constantly playing match maker, which is fun in it's own right but really not necessary for most of my play throughs.
Just delete the one that has the least amount of value to you or one you know you'll never come back to. It's not an easy decision, trust me I know, but if you want to do a fourth play through, something's gotta go.
You know, I've never actually paired those two up before. I always though pairing two calvary units together is like a big no no in Fire Emblem or in strategy games in general. Maybe I should try it out during this new play through.
Hahaha! This game is truly addicting so I don't blame you for playing some more. IT BECKONS YOU!!!