I am trying to find a way to get my database to recognise that a person I am adding to event D is the same person that attended event A. At the moment, when I put Joe Bloggs into a subform under Event D, it is generating a new Personnel ID, rather than realising that Joe Bloggs already exists. Is there some way I can get the subform to add a person if he doesn't exist without creating repeat IDs for those already on the database?