Well, Maxer made some interesting suggestions and we have seen your answers
1.- It would be possible to select any kind of geometry as "collision object"? In collision objetct dont appear proxis. With this option we can distribute proxis in some parts of terrain and delete other parts. We know mask, but for we is a lot better this way of work. Some kinds of fallof near collision object would be great
2.- It would be possible to select more than one proxy in vrayscatter? We prefer select all our trees and put some % to distribute it. Similar to dialog in "material by element" in max. It would be great too can select some maps to distribute each kind of tree, we think it would easy for you
3.- Some dialog similar to "material by element" but with proxis would be great. You could put a lot of materials in ids you can in each proxy. Scatter texture is not bad (if you use as a mask in blend material is the best solution) but "material by proxy" would be a lot better
4.- We have read something but some regular ways of distribute proxis would be great. Distribute as a array 5 meters X 5 meters for example or better distribute along a path

One minor thing. Is not logical that you can up the count of preview when it is more of count in distribution. If you have only 5 in distribution you mustnt can choose more than 5
This is all for now. Thanks for support