Sure no issues splitting up your travel party. In
MDE you select the travel group first or just a subset, then the park, then the attractions (up to 3), and then complete the purchase.
Note: you do need to have your plans linked in Family & Friends in MDE if for example you want 1 person to book two LLMP and/or LLSP for 2 people, and have the same return times for both of you.
Does this make sense?
Dave