It would be nice if the « overrideMirror: True » on parts themselves would work, rather than having it on the main model

Ok, I should also add that overrideMirror doesn’t work on everything, some « custom » types part will ignore the overrideMirror

Will get with the current pack authors to make sure this doesn't affect them. Otherwise, wouldn't be a bad idea.

Didn't hear from authors, so figured it's fine. Use overrideMirror in V15.4.0 now under the "general" section for parts to make them never mirror. Same goes for vehicle JSON under the "parts" section. No double-mirroring logic anymore.

I don't follow. What use-case is this that you are having this issue on? Like what configuration?

And the suggestion is to make that « override mirror » work from the parts json too

When a part has « overridesmirror » it doesn’t work, it only works when the « override mirror » is in the main car

Well yeah. Because parts don't have that. What exactly are you trying to do with your parts that the part needs to implement that logic?