To determine if the character you are looking at has any close relations in play, you will need to look at the family trees and at +cdb/rlist <name> to find the relations. You will then need to look up each related character using +cdb <name>. If they are listed as a PC, they are in play. You can also use +cdb/search state/pc to produce a list of all current PCs, but that list can get very long. Alternatively, +cdb/search house/<name>|state/pc will show you all PCs from a specific house, and that will be a much shorter list.