That depends a lot on your state support guidelines
. Check those guidelines and see if they allow consideration of other children. As a rule, however, judges are extremely reluctant to REDUCE an existing obligation for children entering the picture after that obligation was in place. They figure that you already knew you had to support the existing children when you had the new ones, and should have taken that into consideration.
In other words, the new children might help in preventing an INCREASE in support, but it's unlikely a judge would allow a DECREASE because of new children.