Thai visa for citizens of Myanamr

I hope someone out there has the answer for this question.

Me: an old, retired American, living i Thailand on VA disability. She: Burmese, living in Thailand on a workers passport, worked as housecleaner for her sponsor, as a cook, studied massage and managed a friends m.c. and car rental shop sometimes. She had her health and savings depleted by cancer. We fell hard for each other. We looked into getting married in Thailand and found it was not permitted - the Burmese government is blocking most or all marriages between Burmese woman and foreign men.We learned about visas to the U.S. for a fiance and this is very complicated and moreso for a Burmese and an American..

She decided that she could get the marriage approved if she applied directly to the govenrment offices in Yangon, and get her new, official passport and get a visa there to go to the U.S.A. with me. She ran into a wall on the first step - they said no to marriage to a non-Buddhist. i am cool with Buddhism, but I will not give up my religious freedon. The second goal, the new passport she got today. And she is ready to return to me here in Chiang Mai, entering thailand again using her old workers passport.

The question - which i did not think of uintil now - is is my girlfriend supposed to get a regular visa to enter Thailand on her regular passport?

Is there anything wrong with using her old workers passport to re-enter as she is acccustomed to do?

And is it feasible for us to get along term Thailand visa for her here from Thai Immigration? That will give us time to wok on a U.S. visa for her.

Any advice would be welcomed