Should I create a duplicate person and add it to them? Should I just wait? Thanks
You have a choice:
I generally prefer option #1.
The Family Tree Hints system has no trouble finding those historical records even though they are hidden.
@JacobRencher, if you can "see" the living relative's profile in your private/living tree area, then you can just attach the source to the living profile just like you do with a deceased person. If you do not have that relative's profile in your Living area, then yes you would need to create that person in your living area. Note the PID number from your copy of that person will not be the same as the PID number from any other place that person resides. Same person different PID.