You could look into SVN, I have not tried it myself for such an undertaking, bit over the top if you ask me.
CTRL + V is paste
Most likely, you are trying to copy events which have local variables, you could make them global first, drag them to the upper level, and copy them to the new event sheets before copying the rest of the events. Afterwards you can make the global local again, by simply dragging them to their old position as they were in the previous project.
Who dares wins