Will child support be increased even though we have 2 other children?

My husband has a 12 year old child from a woman whom he had a relationship with as a teenager, but they were never married. For years, she has always purposely tried to make things difficult for us. She calls threatening us for no reason, etc. My husband has always been responsible and has always paid child support faithfully each month. We recently purchased a new car, and when she saw this, she immediately filed for child support stating that my husband's income increased. What's worse, she won't work-or she refuses to work hoping that my husband will have to pay more money. It's funny, because I spoke with her earlier this year and she told me that she was working in a hospital. But when we got the summons for Child Support, there were 0's everywhere, as far is her income is concerned, where she worked, etc. She is living in section 8 housing, collecting money from the government, but even though she is perfectly able, she just will NOT work. In the meantime, my husband and I work everyday busting our es just so that people like her can get free handouts from the government. Now please know, I am not criticizing people who get goverment istance because there are some out there who really need it. But people like her are what I like to call welfare queens. It is not that we don't want to take care of the oldest son, because we do. It is, after all, my husband's responsibilty since it is his child as well. Anyhow, now that we have 2 children of our own, will the judge give her more money just because we got a new car? She has always told my husband (especially when he and were first together 9 years ago) that she would break his pockets. And now that we are living our lives like normal people, any big purchase that we make, she thinks that she can get more money. Geez, I can only imagine what she will do when we purchase a home next year. Would we have to pay more now that we have 2 children of our own? We live in Maryland. Thanks.