Your bigger issue likely is that it sounds like she is asking to change parenting time and defending that could be more important to you. The child support should not be a big deal. You should file a response within 21 days as to her requests and in that you can state that he is in prison and makes no money. Both parties will have to file a sworn financial statement and on that you will state that he is unemployed and makes no money (you might even be able to "stipulate" or agree with the other side to the child support based on $0 income for him). You might hire an attorney at least for a couple hours to look at what they are asking for in their motion and what your next steps might be. Lots of the lawyers here will help on a per hour basis with no retainer. Hope this helps.
You can reach Dave Rich at (303) 886-2516 or firstname.lastname@example.org. Dave Rich is an attorney licensed in Colorado. Answering your questions does not create an attorney-client relationship between us. You should speak with an attorney to whom you have provided all the facts in your case, before you take steps that may impact your legal rights. I am not obligated to answer subsequent emails or phone calls unless you have hired me. I wish you the best of luck with your situation.