You are in luck, then. You can setup everything as I mentioned in my first post above. With each FP+ selection you can pick the family members, attractions, and times.
If you are going to be riding 2 rides together and only splitting up for the 3rd, the best way to do it would be:
1. Make your initial selection with all family members selected and pick the 3 attractions you want to ride. For the split one, just pick Space Mountain for everybody for now.
2. Once you have all 3 attractions and have selected one of the 4 recommended time layouts for the day, you can alter the times to fit your needs. Just go back in and select "Change". You can then to select attraction you want to change the time for, pick "Change the time", and select all members of your party. You can setup specific times for each ride to suit your needs.
3. Once you have your times all lined up, go back in and select "Change" again. Pick "Space Mountain". On the next page pick "Change the Experience" and put a check mark next to each family member not riding Space Mountain. After you pick Next you can select a new ride that will apply only to the people selected. The ride you pick for them will have the same time window as the Space Mountain FP+ for you and your daughter.