When each worker is found, update the associated plot flag. If you want the journal to reflect who has been found, have a journal text associated with each plot entry that states "X has been found". If they can be found in any order, it would be best to organize them as child plots of the parent plot (the alternative is to have plot flags for each combination).
Check this thread out, it has a lot of useful information on this -
http://social.biowar...4/index/2353801