If this lakorn story line is like what I think it is, then this lakorn is probably a remakes of an old lakorn played by Nok Sinjai called "Sia Paye"(the string that use to tie the baby hanging basket). If is the same storyline then Donut should be Namfon's daughter, but is not her real daughter ... she adopted her after they took away her son, but Donut doesn't know she was adopted. She only knew that her mother doesn't want her to have anything to do with the P'ek because she knew that he's her son and the family will dislike her daughter as they did her. And something happen that make her used the "sia paye" to killed someone and her son became lawyer and will do anything in his power to put her in Jail, but his father beg him not to, ... then later he found out that she's his mom.
But anyway... it might not be the same storyline... but from reading and watching the teasers so far, I think is likely is that lakorn, they just changed 'sia paye' to "harb".