How well do you get on with the parents? Negotiate. I was initially told 5 baht gold but then they said nothing because you take care family and love daughter. IMHO if the lady has had children, worked in a bar or been in a relationship before then Sinsod should just be a token amount of gold say 1 or 2 baht. Any cash on display at the wedding should be clearly decided whose it is and what happens with it after the wedding.