Help with dragons

Well I pulled 2 Adult Tikis, one w/ -HP +RES and another w/ -ATK + RES. Is it worth to pick one of them (the -atk +res to be precise) and inherit lightning breath+ to another dragon?
Or should I merge them?

I have Young Tiki (neutral), Fae and Corrin (F) (both are -hp +spd) as candidates.

Any help is appeciated, I'm kinda new to FEH.
Thanks in advance!