Do you want to come to Fred and I’s house?
WRONG.
My mom and I’s recipe for snickerdoodles is great.
WRONG.
Sally and I’s baby is gonna be real smart.
WRONG.
The word you’re looking for is:
my
Do you want to come to Fred’s and my house?
My mom’s and my recipe for snickerdoodles is great.
Sally’s and my baby is going to be smart.
Granted, this all sounds pretty fussy. You’re better off just rewording the whole sentence.
Do you want to come to our house?
Our recipe for snickerdoodles is great.
Our baby is going to be smart.