Not sure if I'm misunderstanding what your issue is, or if you are misunderstanding how the cumsrc option works.    The option is only relevant in 3P+ animations and is almost entirely unused by current animations. Due to how the cum settings were defined in previous sexlab versions and for the sake of simplicity and backwards compatibility, you can only define one actor as the source per stage. In retrospect, this definitely limits the use of the feature greatly and I should've made more of a