Render layers Vector Blur Compositing

Hi

I need to comp an animation with three render-layers, I know you can use Z-Combine to combine the Depth, but how do you combine the “Speed” nodes to apply Vector blur with all layers combined? I guess one way is to apply the Vector Blur nodes just after all the image-load nodes per render-layer and then combine everything after the vector blur nodes with alpha-overs, but this then mean duplicating this setup for every other pass as the exact vector blur needs to be included in all other passes per render-layer. It would have been a great to have a “Speed-Combine” node as with the existing “Z-Combine”

Any advise would be great.