Does anyone know if and how it is possible to 'lock' a Bom so that it could not be updated by a replace all for components?

Dear ukspmc,

We implemented revision control to handle this and other matter regarding BOM change. With revision control, each change to BOM has to be given a revision number. Hence, every change can be tracked and kept in history. To make the control stronger, we disabled full authorisation on the BOM maintenance screen and only give print/display authorisation. This makes the users have no choice but to log the BOM change through revision control

Rgds,
Paul

Note that revision control works well for EBOMs, but PBOMs can still be maintained separately, even though they're linked.

The best control is restricted access to the maintenance session. If you're using Replace Items in Production BOMs (tibom1212m000) and want to exclude one individual BOM, I don't believe there's any way to do that, though I've dealt very little with that session. With ECO's and revision control, all our changes are run through EDM and the ECO change process.