The simplest way would be to add the ball mesh to the model, and set all vertexs coords of this mesh to (0,0,0) for every frame (in other words, reducing the ball to the size of a point hidden inside the main mesh),
except for the ball animation frames, where all the other meshes have their vertexs coords forced to (0,0,0). All of this can be done in QME in 15 minutes (including 5 minutes to take a leak

). The main problems in this approach are the waste of memory space and the weird morphing when switching animations if your engine supports lerping.