I've been using multiple runtimes for a while now, with separate libraries for each figure. The problem then is having to keep going back and forth between runtimes for general purpose materials, multi-use texture maps, and stuff like that. Then I found out that shortcuts work. Add a shortcut to /Runtime/libraries/Hair/NiftyHair/ to /Runtime A3/libraries/Hair/ and bingo, NiftyHair appears within the A3 library. Suppose you have /Runtime/libraries/Materials/Multi-use/.../... /Runtime/libraries/Materials/Multi-use/.../... /Runtime/libraries/Materials/Multi-use/.../... Then you can make a shortcut to the Multi-use directory in /Runtime A3/libraries/Materials and you'll never have to leave the runtime again.