After doing research in the forum, I could not find a similar case so I will try to briefly expose my mother-in-law's situation and hope to hear your opinion about it.
She wants to come to the US to visit her children that are US Citizens. She is still married to their father (naturalized US Citizen in the 1990's), although they have been separated since the mid 1990's but are still officially married. Never really got divorced. She had a green card that was abandoned in the early 2000's and haven't returned it yet which I assume is the first step to take.
She has no intention to live in the US but also doesn't work or own property in her home country as she is supported by her mother that is sick and she currently takes care of.
Would it be advised for her to come to the US with the intention of divorcing her husband or can she prove she is not willing to stay without doing so? What would be the options or next steps she should/could take?