Originally Posted by
serpens
I'm confused. It sounds like you are suggesting each of your parents-in-law get an open sleeper ticket, but the open sleeper ticket allows the holder to join someone in an already-booked room.
If I understand the situation, I would suggest you reserve a room for your mother-in-law and add your father-in-law on an open sleeper ticket if he can make the trip. In this case, I would not book the open sleeper ticket until he is confident he will travel; that way, there is nothing to cancel.
The latter is what I meant - wife and I are definitely going in one room, and mother in law is definitely going in another room. Thus, I was thinking either adding my father in law on an open sleeper ticket later, or adding him from the start and seeing if I can cancel just his ticket later (but keep the room for her) if he decides not to go.