Can my parents extend their stay in Thailand by leaving and re-entering before their visa expires?

Good morning. My mother and father arrived on a 30 day entry in Chiangmai on the 19th(Dec) by plane. They are staying until March 14th. Is it possible for them to go to Mae Sai border crossing before expiration(January 17th) and come back in with a new 30 day stamp and then get a one month extension on their new 30 day from Mae Sai giving them enough time for their International flight home? Thank you in advance.