One common workflow is the "household" survey. There are several different ways to address this use case, which commonly requires the ability to link a set of individual cases with a household case.
Use Case 1: Register a household and visit family members multiple times (data linked)
Structure
Module 1: Household (case type = household)
Form 1: Register a New Household (registers a new case)
Form 2: Register a New Family Member (updates or closes a case; opens a subcase of the case type person in the Family Member module)
Module 2: Family Member (case type = person)
Form 1: Family Member Follow-up (updates or closes a case)
Form 2: Remove a Family Member (updates or closes a case)
Comments
This particular workflow allows a mobile user to register a new household, then choose that household from a list and register any number of individuals. To follow up with those individuals they have to go to the second module, which will contain a list of all individuals. You can then search for the household name or use Multi-level selection in the case list so that you first pick the household, and then pick one of the family members to follow up with.
Use Case 2: One-time survey where you just want data linked by household
Structure
Module 1: Household (case type = household)
Form 1: Register a New Household (registers a new case)
Form 2: Fill out Survey for Household Member (updates or closes a case)
Form 3: Remove or Edit a Household (updates or closes a case)
Comments
In this case you are just registering the household and then filling out individual forms against the household. You are not creating child cases for each individual, so the case list will consist only of households. Choosing Form 2 or 3 will pull up the case list of households. Form 3 is required so that there is a way to remove the household from the case list, or to change details.