Simplify Add Family Member flow to avoid leaving the Add Person screen

[ctsutherland]

Is your feature request related to a problem? Please describe.
A user may get confused when adding a Family member during the "Add Person" process. Current flow:

1. User is on the "Add Person" screen, creating a student account.
2. User clicks +Family Member.
3. User is taken to a new screen — also titled "Add Person". At this point the user may think the process has started over, or that they've lost their original screen.
4. User clicks Add Person on this second screen.
5. User is taken to a third screen to enter the family member's information (name, gender, etc.).
6. User clicks Save and is returned to the original Add Person screen, where they were creating the student account.

Describe the solution you'd like
A simpler flow, with less opportunity for the user to feel lost, would be for +Family Member to open a drop-down information form that can be filled out without being taken to new screens. The student's information should remain visible the entire time the user is adding their family member.

Describe alternatives you've considered
Just the drop down information screen, or another option that would allow the user to remain on the original Add Person screen throughout the process, rather than being taken to another page.
Possible short term fix - Change the "add person" button on the second page to "add family member," and have the info form drop down on that screen. This would eliminate one additional screen the user has to navigate, as well as clarify that the process has not started over when they're taken to the second screen.

Additional context
Screenshots below show:

1. the Add Person info screen, where you click +Family Member
2. the screen that clicking +Family Member takes you to, also titled Add Person
3. the final information screen you reach after clicking Add Person.