There is the situation of “co-marketing”, where two companies (A and B) sell what is the same product but under two brands:
Company A produces as CMO for B but also sells themselves
Company B has no own production
In conclusion, A would be the obvious OBP, also because only they have the repository system.
However, as A and B are completely separate legal entities, not parts of the same group (though they have a commercial agreement in place), Company A cannnot upload on behalf of Company B, because they are not affiliated to each other.