No way to make Vanilla objects assignable to Mod objects

[qcs2017]

Via the IAssignable.IsAssignableTo() I can make a modded object assignable to another object. Unfortunately, although assignments should always be mutual (if I can assign one object to another, I should always be able to assign the other object to the first), the game does handle that in two instances. This is static and makes in impossible for Mod objects to be assignable to other objects which are not under control of the Mod (like Vanilla objects, or objects from other Mods).

[qcs2017]

AssignableObjectManager.OnLoad() checks if the assignability is mutual, and because it isn't, it does not load the assignment. I'm blocked.

[qcs2017]

I was able to create a workaround for the loading issue, so it's not blocking me anymore. However, the issue is not gone. Especially that I can assign a Mod object to a Vanilla object, but not the other way around. :)

[qcs2017]

Problem with doing the load/save on my own: If the mod gets exceptions while running, it gets disabled, when players then save the airport, the assignments are not saved.