I have a question on child suport for a mistress?

Ok heres the situation. I am in the middle of my divorce me and my husband came to an agreement for child support we also agreed that he is going to move out and pay the mortgage until it is sold so he will not pay child support for our 3 children until it is sold. During our marriage he had a baby by his side chick a mth younger then my 9thm old. me and him drew up a paper with the amount of suport he is gonna give her for now until our bills are paid off. Well she was down for it before but now shes like tell her to stay out of our business. She is a young girl this girl. So she is hard to deal with. My thing is no one asked her to deal with a married man and have his baby. We have bills to pay off so both of us can move on with our life. She said she talked to a lawyer and can get alot more whic i dont think is true as we have way to many bills and have 3 children she knew he was married when she got involved with him. by all means no one is tryin to give her baby less cuz i have gone out and bought diapers formula, clothes, furniture for that baby. my question is can she get more money or does the judge look at his family expenses first?