http://www.tesnexus.com/downloads/file.php?id=25213 are awesome IMO and when I played OOO I could have them replacing the vanilla ones via MadCat221's OOO Xivilai Replacer that comes with the download. Used with FCOM it only works with summoned Xivilais (and the CreatureXivilaiNOSUMMON), though - the rest is vanilla.

So far I've tried to just add it last in the load order and also to load it before the Bashed Patch, adding relev and delev tags (besides the Eyes, Hair, NPCFaces, R.Relations that BOSS already gives it), but neither works.

The vanilla Xivilai is a creature and Slof's are NPC's and as it seems MadCat221 has altered leveled lists to replace the creature with the NPC's, I guess the issue might be with FCOM using other leveled lists than OOO perhaps?

Anyway, seems it shouldn't be rocket science to make an FCOM Xivilai Replacer patch but it's beyond my very limited knowledge of leveled lists etc. Perhaps it can even be done with some Bashed Patch magic? Anyone who has an idea on how to do it?