At the beginning of the wedding,
the mothers (and grandparents) are seated just before the
processional, so on the program state "Seating of the parents"
or "Seating of the parents and grandparents." By saying
parents, your father-in-law is included as he walks in with
his wife. On the portion of the program where you list the
participants in the wedding, be sure to list the parents and
The parents are not introduced
at the reception unless they make a toast. If you are having
a grand entrance of the wedding party, the parents do not
participate in it.
Glenna Tooman, ForeverWed.com