Child Support

If the father of my child has 2 children from a previous relationship would that mean that he is required to pay the appropriate table amount to the previous relationship for the 2 children and the table amount to me for one child? Or would you look up the table amount for 3 children and he would pay her 2/3 of that amount and the other 1/3 to me?

Thank you for any clarification you can provide.