If you want to merge the runtimes, first step i would do, copy all the Libraries on an external harddrive, so you will have a proper backup. Then you can merge Runtimes. The main reason i have done this in the past was to avoid double entries. Seems no big problem, but if you start a search and you get the same item three or more times, it annoys me. Also working with the material room is easier if everything is packed in one Runtime. In my case, i had 5 runtimes, one for V4/M4 figures, one for props and buildings, one for project evolution, one for V3/M3 figures and one for stuff i created by my self. Nowadays i have merged the first four and keeped the last on it's own. The downside is, the library is rather large and poser 11 gets pretty slow, browsing the content is not very pleasant. I have made some hard decisions regarding my content and sorted out quite a few items i haven't been using for a while or even not at all. Hope that answers your question and i wouldn't be glad if it helped.