become
We'd just write an ECO to do something like that. It's effectivity could be restricted to certain unit serial numbers, or to an assembly rev letter, or it could allow production to do it at their option as needed. If a board got that ECO incorporated, we'd have the records.
All of our ECOs have a stated effectivity, namely a statement of when the ECO is to be applied. We can write an ECO that applies to a single serial number, like a special for one customer. Or an ECO can create a new dash number, a new standard version of a product.
John