An Associate List

When interviewing a relative, consider asking them for names of people they remember and how they knew those people--neighbors, relatives, coworkers, people from church, etc.

Asking a person who they remember from work may help to jog their memory about other things and keeping a list (or a chart) of people your relative knew and "how they knew them" may come in handy later.

When interviewing, don't be too concerned about precisely how two people are related if the interviewee can't remember. You don't want to frustrate them and armed with a name you may be able to determine the relationship later.