Let's say,
I filed a USPTO provisional in Jan 2019.
I filed a USPTO non-provisional in Jun 2019 by claiming priority to the provisional.
I'll file a PCT application in Dec 2019 by claiming priority to the provisional. But this PCT application contains "new matter". The PCT application is valid till Jun 2021. [i.e. 30 months from the provisional]
Now my question is, Am I allowed to include the "new matter" in the USPTO non-provisional via some amendments? How does one can claim priority when the amendment submitted 1 month before the PCT application expiry date? i.e. May 2021