Both attached surveys (.srv files) are an example for the child survey technique.
Here is how to import it into your organization:
How To Import A Survey (SRV File)
The "Parent survey sample" survey captures names and ages of household members. The names and ages are captured within a loop chapter that iterates on the HH members amount entered.
Once the loop is complete, the "Child sample survey" is automatically opened. In that survey, we ask some questions on all HH members that were entered in the Parent survey, but only those who are 21 years old and above. The way it is done, is by creating the loop chapter in the child survey, that iterates on the same amount of HH members, and enter each iteration only if the age of the HH member that correspond with this iteration number is 21 or more (see the code in the iteration start script that pulls the age value from the right place in the Parent survey). Inside the loop, we ask few simple questions, and in each we display the current HH member name and age, that are pulled again from the Parent survey.
Important note: Make sure to import both surveys into your account, and in addition assign the "Child sample survey" survey as the child survey of the "Parent survey sample" survey, as explained in the following HowTo: http://support.dooblo.net/entries/26142561-Child-Surveys