cucurucho

Which version of more nasty critters are you using? fomod or normal? be sure creature framework plugin is really enabled using your mod manager, I've suffered some issues in the past with other mods using wrong fomod settings and not all plugins or resources were installed correctly.

wait a minute... are you installing creature framework + more nasty critters? Install only more nasty critters, this pack contains creature framework and other related mods, so you don't need them. Probably you have a version conflict with original CF and CF installed with more nasty critters.  

Be sure needed meshes aren't missing, go to creature framework MCM and see which option is using each creature to find possible registration issues, use re-register all option if needed.  

After installing these mods, try to overwrite with latest version from original Jcontainers (some mods couls contains obsolete versions that overwrite new ones), since game only work if you remove files manually seems to be a conflict with scripts or plugin versions...  

Note that FNIS and Sexlab framework have separate files for creature support, you also have to install them, and be sure other mods don't overwrite required files with obsolete versions.

Be sure all plugins included with More Nasty Critters are loaded in recommended order and don't forget to run FNIS after installing any mod with custom animations. If you do these thing but issues persist, try to reset animation registry in sexlab MCM.

Great and inmersive mod, only two questions. What about a mixed option for birth? First you have baby items and after some time carrying them, they are replaced with actors, for example when belly replanish time ends, so you don't need a new event.   And items based on father race?   Humanoids -> babies Undead/Magical creatures -> soul gems Spiders/chaurus.. -> Eggs ........