Do you have a Deviation or Waiver procedure in place?
The way we work out "development" changes to a production part is to create a Deviation. This Deviation applies strictly to a specific revision. In other words, you are currently at RevB. You create a Deviation against RevB and give your new vendor the RevB drawing and the Deviation. He quotes to that and makes the tool to both the drawing and the Dev.
In the meantime, Supplier 1 is still happily in production and making changes to RevB. To document these changes, you revise the drawing to RevC.
Now the tricky part. Supplier 2 is working to RevB+Deviation. You can either update his SOW with RevC + a new Deviation, or keep going as is. Once he is online, you give him RevC to work to because it is now your active rev. Or, depending on the content of the Deviation. You revise RevC to RevD and Supplier2 works to RevD. Supplier 1 is effetively out of the loop.
This is very similar to the way the government handles NORs (Notices of Revision). Basically, the contract states create to drawing RevC and NORs 1, 3, and 4. Another contract may be just to RevC. Other may have other NORs. When the government finally revises their drawing to RevD, all the current NORs get incorporated. It's confusing, a real PITA, but it works and saves money but not having to go through the ECO process to correct a typo.
--Scott
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