Start by adding a new Contract Status.
Then, set the child machine that is due to be Finished to this new Status.
Now on the master, go to the Linked Machines tab, find machines on PendFINISH, right click and select Finish on Variation.
When you the Variation to the New Meter/Contract setup, the differences will show that machines set to Finish on Variation show as Removed
Then a quick check of the PendFINISH Machine to see it is now at FINISH.
Further information