There are ready-made invitations for sale now. Just fill it out after you buy it. Fill in the name of the invitee in the first line, the place and time of the banquet in the middle, and your name in the last line.

If they are all written by themselves, write the name (address) of the invited person in the top box of the first line, and write the time of the banquet (when and when) in the second line to hold a one-hundred-day banquet for the granddaughter. The location is in XXX hall of XXX hotel. Please write your name on the last line. take for example

Xxx (address):

A hundred-day banquet will be held for my granddaughter in the xx Hall of xx Hotel at X: X: X: X. Please come then!

Please call Xxx (your own name).