I have probably dumb question, but I like to ask it anyway: if I replace an object reference with a copied (base) object, then does this will break precombines/previs? For example, there is an object reference to a bed. I made a copy of the (base) object, let's take NpcBedGroundSleep01 "Mattress" [FURN:0002FBF9] from Fo4 and named it as my_NpcBedGroundSleep01. After that via xEdit I have changed "Name - Base" of the object reference from NpcBedGroundSleep01 to my_NpcBedGroundSleep01. Note that my_NpcBedGroundSleep01 contains only "cosmetic" changes, like another set of keywords, but the NIF is the same as for original record NpcBedGroundSleep01. Do I need to rebuild precombines in this case or not? Thanks. Update: 1. I have figured out that there is a case, when there is no need to rebuild precombs/previs. If an object references has not referenced by a parent cell/location (in XPRI/XCRI records), then it is not a part of precomb. This object ref would just be rendered in the game at runtime. 2. It is also clear, that if there are no changes to NIF, then there is no need to rebuild precomb. But the question about regenerating previs data is still open: do uvd files contain any information about the base object (not just NIF related data), so if the reference to the base object would changed then previs would be broken?