Before you slam me for this, read everything first.
I know guests who are over 18 and lives with parents or siblings gets their own invite.  But what if those adult guests request to put their names with their parents'/sibling's invitation to save the money on postage and invitation.  Note:  this is their request, not mine.  What to do in this case?  Respect their wishes and put it into one household or ignore it and give them their own invite?