[AbleSeaman]

I need some info on reducing relative clauses.

I broke my plate which had been engraved.
(I have got lots of plates but I want to make it clear it was the engraved one I broke. Defining.)

There is no subject, as it's passive, which is fine when it's not reduced but makes it sound wrong if I reduce it.

I broke my plate engraved. Certainly wrong. We couldn't reduce to this from the past simple (...which was engraved) either. Yet in other contexts the same construction sounds OK (I liked the last song played OR I think the best was the third goal scored.)

If I add a prepositional phrase and change my to the, it sounds OK.
I broke THE plate engraved AT THE FETE.

I can't find any information that gives rules for the situations I have described. There is some to say that we only reduce if the verb after the relative pronoun is 'be' but that wouldn't explain the issue with the past simple. And some people think we must leave the subject in for passive reduced relative clauses but I see and hear this not done plenty of times.

Help, please. Thanks in advance.