I cant say I know anything specifically about this process, but from a
general api perspective, it seems that specifying multiple source arguments
as an array isn't documented in either the MEL or the python api docs.
What the docs do say is that it does expect source and destination flags as
In cases where I want to transfer weights from many separate meshes to a
merged version of all those meshes:
So I have done that many times in MEL land using:
$sourceMeshes - an array of meshes
$targetMesh - single target mesh
copySkinWeights -noMirror -surfaceAssociation closestPoint
