5753568 I think I remember seeing one a while back, but it was so long ago I can't remember the name...

5753568
I can think of a number involving half-changelings:

My Fluttering Heart involves a half-changeling adopted by Cadance and Shining Armor.

Bakki's "You Are the Father" is a (dialogueless) comic about Chrysalis dropping off her half-pony, half-changeling kid with Shining Armor and Cadance.

A Changeling Effect is about Chrysalis dropping off her half-pony, half-changeling hybrid offspring with Shining Armor and Cadance. I can't really recommend it from what little I've read of it, but I haven't read much of it.

It's a... Pony? which is about Chrysalis dropping off her half-pony, half-changeling hybrid offspring with Shining Armor and Cadance. I haven't read it; I found it via searching.

And found a few involving full-blooded changelings:

Little Loveling, which I also found via search. Haven't read it.

We'll Always Love You, which I can't really recommend.

Love Is Blind, which I also found via search. Haven't read it.

5753568
"My Son is a Changeling" I think is sort of in that ballpark as well...not 100% sure though, been a long time since I read it.