Child to parent or younger generation to older generation. Third person is used.
With your parents you use MA or PA. With relatives and friends and some strangers you use TANNIE and OOM.
An example:
Hallo Oom
Volgens Amazon het my pakkie al by oom-hulle uitgekom, het oom dit gekry?
As oom dit gekry het, kan oom dit asb. pos (die goedkoopste spoed) en net vir my die bedrag email.
Baie Dankie!
Annie