Upgrade near coastal license to oceans using mate of towing (toar)?

I’ve heard it’s possible to upgrade your 1600 ton NC with a towing endorsement (toar) to oceans just by taken a credited maritime celestial class and turning in the certificate to your local REC. I’ve also been told that you don’t have to do all the sailings if your putting the oceans endorsement on the towing endorsement, not your license. Is there any truth to this. Seems like an easier route to go to get oceans. Feed back on this is much appreciated!