A "bounce" theory of light reflection is required to assume Michelson-Morley (less ether interpretations) demonstrates c constancy. An incoming quantum, George, is the outgoing quantum.
A "catch & throw" theory would suggest that M-M does not demonstrate c constancy, that George arrives and Mary departs. Like a baseball pitcher's fastball being returned by the catcher at his own velocity. Hence, per such a theory, M-M would demonstrate nothing about c+v.
What does quantum theory say about this matter?
Similarly, please, in regard to refraction.