honestly it sounds like you NEED a lawyer.
your husband is going to have to fill out a financial affadavit showing his debt to income ratio, any assets, likely they will want paystubs, w-2 past years income tax, etc....
the child with a support order is ALWAYS going to come before the child WITHOUT one, even if the child without one is OLDER.
this was Nextwifes point, if in the future you and your husband do NOT stick together, the figure the court will use to set YOUR child support, for YOUR child, will be figured, after the support for this other child, is minused from his income. (example- your husband makes 50,000 a year, but pays 10,000 in support. the first childs support will always be figured on the 50 thou, but your support will always be figured on 40,000)
it depends on the state, but any children you have with your husband now or later, will likely only count for a small percentage credit towards his income used for child support, In my state the child I have with my husband is worth "2% off" any attempt his ex could make towards a raise in support.
As you can see not really worth having ANOTHER child for him to support, especially if you are worried about the possible support he will be paying now.
again you guys need a lawyer.....