So the idea is that you need separate scatter for each member of the group. They need to be identical to each other in any way, except for the list of instanced models, of course. Most important things to keep in mind is that all members of the group must share the same pivot point and transformation and they need to be added to their respective scatter in the same order. Also, keep in mind that scatter features that are dependent on instances' bounding box, like collision avoidance and area exclusion will not work, unless each member of the group shares exactly the same bounding box, which is doable with some simple hacking. Another important point is that each group has to have the same number of members, otherwise everything will brake apart (again, solvable with inclusion of dummy members). I didn't try yet how easy, or hard is to wire every parameter of multiple scatters (i guess simple instancing will not work, because of requirement to have different instanced objects in each scatter). In theory, you should be able to wire several empty scatters together, save them to a file and reuse them in any scene by simple operation of merging.