There are several ways to go about it, but, if you are concerned about making FP+ reservations for everyone and getting the same times, the easiest thing to do is to book a room-only, put everyone (you, DD, DH and Mom) on the reservation and then buy everyone's tickets separately (example - 10 day ticket for you and DD, 7 day ticket for DH, 3 day ticket for mom - make sure you link these tickets on
MDE). The only issue is, you will charged the extra adult fee if both your mom and DH are on the reservation the whole time ($10 per night for values, $15 per night for mods, $25 per adult for deluxes). However, if you do this, you will be able to make FP+ for everyone at the same time and set up Magical Express for everyone as well. You may be able to get your mom's and DH's extra adult charge dropped when she leaves the room by going to the front desk, but that is definitely not guaranteed.
You can make a room/ticket package reservation for 3 and then drop your mom and add DH when he arrives, but everyone on the package has to have the same length of tickets so you will be getting into a situation where you and DD won't have enough tickets for your entire stay (you can upgrade them at the resort) or mom will have too many and whomever is not on the reservation will not have 60 day prior FP+ reservation privileges. (they can have 30 day FP+ privileges, but the chances of them matching up to those that booked at 60 days is slim to none) or Magical Express until they are officially added to the reservation. I know - it's complicated.
I would just do room-only, buy your tickets separately and ask the front desk to drop the extra adult charges when you check in.
