Cooperating sceneries..

Hi all-I had a question regarding the addition of scenery to FS9. Having made the decision to stick with FS9 for the foreseeable future, I've been adding quite a few scenery packages and was wondering something. I looked in the scenery library and have found all the addons (UT, Freight Dogs,Cloud9 KLAX and so forth)there stacked by order. Does the order in which they appear cause another 9the one below) to be overwritten? For example, I just added Freight Dogs and was wondering if some of its scenery it overwrote Misty/Tongass Fjords. Likewise with water textures from Flight Environment. I hoping this is making sense!Thanks,Mark