Understanding Society User Support

Hello,

I have a few questions regarding family connections:

1. I read the user guide for the family matrix (xhhrel) and want to ensure I understand how family connections are formed. As I understand it, information is collected for core sample members and their household members. So if I see a connection between an adult child and a parent, it means that they had to be cohabitating in one of the waves of the survey. Hence, if a person did not cohabit with their parents at any point, I wouldn't have any information regarding this family connection. Is that true?
2. Suppose that the core sample member lived alone in waves 1-3, and then cohabited with their adult child in wave 4, and then the child moved out (from wave 5 onwards). Then, is the child being followed for the rest of the waves (4 and onwards), or is he being sampled just for the wave in which he cohabits with the core sample member (wave 4)?
3. Does the family matrix contain connections made in the British Household Panel Survey as well, or only connections of family members cohabitating in understanding society?

Thank you