Individual Family Member Programs gives you the ability to enroll an individual family member into a program (as apposed to a Program which is assigned to the main record as a whole).
Family Member Programs also support Enroll and Expire date to fine tune the enrollment. Typically, this is used for enrolling of a child in Hebrew School or Camp for a certain period of time. In the past, the Enroll Date and Expire Date defaulted to "Enroll Today for one year".
With this feature, you can define enroll and expire date for each Sub-program. Click Program Setup > Family Programs. Click New (or Edit) Subprogram and assign a default Enroll and Expire Date.
This way, if the subprogram is for Camp, for example, and camp is between July 1 and August 30, you don't have to enter this each time you enroll a child in camp, rather, you set these default dates in connect to the Subprogram and when you enroll a child in that subprogram those are the default dates (which can be changed if you want). If no default dates are set up, it will still default to "Enroll Today for one year" as it was in previous versions.