No need to bring her up at all in court with one possible exception and one definite exception.
Possible - If your state requires an affidavit of expenses, you may be able to request her income to prove an offset of his expenses. For example if he takes home 3k/month and shows his mortgage as being 1.5K you can request her income to show that his SHARE of the mortgage is actually only $345/month.
Definite - If your state goes by "share" rather than a straight percentage of his income and he has a child with her, she has to show her income on a CS spreadsheet to show his CS "obligation" to her in order to deduct that from his available income to pay CS for your child. (For example, my ex married T and she had a son J from another marriage. My ex and T have a baby A. When I was taken back to court to lower CS, my ex and T had to fill out a CS spreadsheet to show what he would owe for A. His income was then lowered by that amount and my CS was then calculated based on that lowered availability and my income.)
If you're trying to get CS from her, you're out of luck and just wrong. She didn't have that child, she's not responsible for that child. Only you and your ex are.