If there is no more Old data ever going to come into the app, you could change the Key field back to Record ID#, and then the unique tracking # would just be a formula field.
I would suggest doing this first in a Copy of your app, if you do not have much experience with change key fields. Quick Base will maintain all the connections between the Parents and the Children.
Normally the only Fixing that needs to be done after QuickBase makes its changes is on the child forms, the fields for choosing the Parents sometimes needs to be fixed on the form.
