Where are the children and how long have they been there? If the children have been in Colorado for at least six months, then Maryland is probably the wrong jurisdiction for the case. If the children came from Maryland and have been in Colorado less than six months, then you will probably have to litigate your custody issues in Maryland. You should sit down with a family law attorney to go over the details.
You can reach Harkess & Salter LLC at (303) 531-5380 or info@Harkess-Salter.com. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
I agree with my colleagues. There are a lot of unanswered questions to the question that you pose. First, what state entered the original orders in your case? Second, where are the children currently residing and how long have they resided there? Third, if neither of you are in the state where the original orders came from, how long have you been in your respective locations.
If, hypothetically, the original orders were entered in Colorado and the children are still residing in Colorado - Colorado would likely still retain jurisdiction. If the children are no longer residing in Colorado, then we would need to figure out what the proper jurisdiction would be to handle this issue - it still could be Colorado, it could be another state, Maryland included.
It would be a good idea to speak with an attorney regarding your issue. Jurisdiction matters can be very complicated and can have case long consequences.