Well for my beloved there is Ch�rie, or if being silly, chevreuil.

For the children: minou or petit chou are the most common.
One of my nephews (age 3) is referred to as Dr. Destructo.

My parents: Aged P (works for both)

Others I remember for my siblings were:

Michaelmouse (Michael)
Lillybets (Elisabeth)
Mugwumps (Marguerite)
CathCath (Catherine)

I don't think my oldest brother ever had such an appellation and, of course, mine is classified.