If you link your reservations together you should be able to make Palo reservations for them, as long as it is a reservation for the 4 of you (not one reservation for you and your DH and another for them). When you go online to make the reservation you will see names to check off for the reservation and theirs should show up with yours...as long as your reservations are linked. You will need to make the reservation in your or your DH's name and then you can check off the other 3 names.
I do not believe you will be able to make spa reservations for her as they are not group reservations. All reservations need to be made in the name of one of the people on your reservation. If it is a group reservation you can add others that are linked to you but not in your party. If it is a reservation for one you can only make them for you or your DH...does that make sense?