TarionzCousin
Second Most Angelic Devil Ever
Tieflings are always trying to make more babies... because they are always horny.
Hey-O!!!

These are just my personal answers, but... no. A tiefling cannot reproduce with an elf or eladrin anymore than an elf can breed with a dwarf.If a human and a tiefling have a child the child is a tiefling.
Can an elf and a tiefling have a child?
Can an eladrin and a tiefling have a child?
In either case would the child be a half-elf or a tiefling?
(I am thinking of a tiefling that is fey-pact, but might also have a fluff-based blood connection to the fey realm, so being descended from eladrin would help with that, even if it makes no crunch difference).