It is allowed in P-Cola. My buddy was an OCS guy, his old man was a retired O-6, and commissioned my boy before the group ceremony.
Any military officer, 20 yrs or 4 yrs in, can commission someone. I did it as an Ensign for a couple of ROTC buddies.
My grandfather (retired USMC O-6) did mine. Great stuff, especially glad to have it on video now.