Create sketchfab annotations with API

Our company would like to use the Sketchfab API to show building constructions to clients. This works perfect, but we would like to use the feature to create annotations on the 3D models within Sketchfab.

I couldn't find anything about creating/editing annotations with the API they provide. This is possible on the site itself.

Does someone know how to create those annotations with Sketchfab from another site (embedded or with API), or knows about a 3D web modeling program/framework which can do that?

Thanks in advance!