@Oksana **********
if they are looking for a solution prior to leaving their home country,
they could consider obtaining a non imm o-a multi entry visa. That would give them a year before needing to deal with anything Thai Immigration related other than the 90 day checks. And if they did a border run just prior to the enter before date that is stamped on the visa they could get a second year as well.
Some state that this is a difficult, complex, expensive visa to obtain and I suppose that depends a great deal on the specific Thai Embassy/Consulate you would be dealing with. I have gotten a number of these visas over the past few years and have never found them particularly problematic nor expensive.