Do guests who are young adults (18-22 ish) but still live at home and their parents are also invited receive a separate invite shipped to the same house? I'm not sure how to invite these guests and I don't want to break etiquette, but it also seems strange to send a separate invitation to my 18 year old cousin when there is already an invitation going to her house for her parents and younger siblings. We have quite a few guests in this situation and I would love to know you're input!