Power to sub-license is granted to a licensee by the party that owns the thing.consider a typical sub licensing agreement
Does it actually say the party that ‘owns’ the thing being licensed does the granting? - I don’t think so. I think it would say the sublicensor grants or something similar. Though you’ve seen a lot more sublicensing agreements than I do I could be wrong.
Perhaps each link in the chain must be considered to create a new property, which can then be licensed onward (rather than sub-licensed)?