Question for Jehovah's Witnesses regarding birthday party/family reunion...?

Okay, here's the story: I'm having an 80th b-day surprise party for my grandma. A portion of her closest family members are Witnesses. They have verbally agreed to attend the party and calling it a family reunion, because we are bringing together family from all over the country. Now I am about to print invitations and would like to know what I should put on the invitations to them? Should I just send the same invitations as I send to everyone else? Or, should I send them invitations saying something like this: ".....invited to a family reunion for the family and friends of Mrs._____ on the day before her 80th year of life." Or, something else entirely? It will not cost extra to have two sets printed and I don't wish to offend or deter anyone.