OverwriteManager.MERGE?

[Steve]

Similar to my other post, I would love a new overwrite mode which would merge, or average the values of two or more existing tweens. Possible?

[GreenSock]

No, sorry, that's a LOT more complex than you might think to have the engine manage that for you (especially when the values could be managed in plugins, there could be more than 2 tweens of the same object's property at the same time, etc.) but you should be able to implement that logic yourself (outside the engine).