Among your various family members, are there any nicknames that derived from the way a baby or young child mispronounced someone's name? ~

Yup, mine. 

Was a guy whose younger twin brothers started calling him ''Dee' for unknown reasons,  his family adopted the  nickname but he managed to maintain his real name in school. 

Yes. My name, Manna, was how my younger sister pronounced Amanda.

"Yes" ... although I'm not sure mispronouncing was the culprit.  My daughter replaced the first letter of my surname with an "R" and called me that instead of Dad.  She still does and has even introduced me using that nickname (usually just to her good friends).

My mothers name was Olga. My little brother used to say Oder instead. 

not that i know of

My husband had an Aunt Tidda.  That came from her sibling trying to say sister.