PLACE drink mix in punch bowl or large plastic or glass pitcher. Add water; stir until drink mix is dissolved. Refrigerate several hours or until chilled.
STIR in ginger ale when ready to serve.
PLACE 1/4 cup sherbet in each punch cup. Pour drink mix over sherbet.
Substitute orange sherbet for the blackberry sherbet.
For a party, prepare drink mix as directed in punch bowl. Refrigerate. Just before serving, stir in ginger ale and drop scoops of sherbet into the punch.