When loading a Maya scene containing stage, possibly through other Maya reference, find the correct layer manager node for the stage. Each layer manager node is specific to the scene or reference.
Add an optional parameter to some layer manager function to specify the Maya reference that should contain the information.
Pass the correct Maya reference, if any, when computing the proxy shape node layers.
Add a unit test to load a stage in a Maya reference.
When loading a Maya scene containing stage, possibly through other Maya reference, find the correct layer manager node for the stage. Each layer manager node is specific to the scene or reference.