We have a group of 8 so when I have been unable to get one reservation, I’ve been doing 2 separate ones. My question is, how far apart can the reservations be and still be seated together? I think we have 4 reservations like this ranging between 5 and 40 minutes apart.
When you book 2 smaller separate reservations, the restaurant has no way of knowing you are one large group so you are assigned two tables appropriate for each reservation size. There's no way to link the reservations so you will have to ask to be seated together when you check in. The castmembers will do their best, but it is only a request and there is no guarantee. Most of the DW restaurants do not have a large number of larger tables so be prepared to wait longer, or to be seated at adjacent or nearby tables or possibly tables on the opposite sides of the room. Even if you have one reservation for your entire group, there is a possibility that you will not be seated together because of the limited number of large tables.
As far as 5 to 40 minutes apart: if you are hopeful of being seated together, the reservations should be as close together as possible - 15 minutes apart would be the most I would risk. Two reservations 40 minutes apart will not be seated at the same time especially if it is at a popular restaurant or during a busy time. Expect that the 40 minutes later reservation will be asked to return at the time of their reservation.
Keep checking online frequently for a single reservation for your entire group so the restaurant knows the actual size of your group. There is a cancellation thread for each month at the top of this page that you can subscribe to, but be sure to read the rules in the first post. Also, many have had very good luck with the reservation finder on Touring Plans.