So marriage is not the answer!
She really needs to know this!
Best to do what Anna said and she should just visit when she can.
Your mother should consult an immigration lawyer who is well versed in these procedures.
She needs to look into the legal aspects-the liability of her property and net worth in case of a divorce.
A consultation with a professional is the best way to go. If you go to your mother with advice she'll think you are just trying to crush her groove.
No one here wants to do that-and hearing from you how this is the wrong way to go about having this man visit her may go in one ear and out the other.
Your mother may think she is doing this man a favor, but this one little act will be a windfall for him and his family in the DR and a potential nightmare for your mother.
There is really nothing to be gained by this on your mother's side.
She can avoid any problems by visiting once in a while, but hearing it from a lawyer may have it sink in. If your mother does read DR1, then she must have some idea as to what she is getting herself into.
Knowing is one thing-knowing and not caring is a mistake that she will pay for dearly.