No. If the decree states that your ex MUST list the home (i.e. not sold by XXX) then so must you. If your ex chooses not to do so, s/he is in contempt. If it does not sell and you choose not to list it, then you in contempt.
No. Changing the locks might prevent the other party (ex) from access to the dwelling which would definitely place you in violation of the order. You and your ex BOTH have the right to occupancy and thus cannot bar one another from access. At least based on what you've posted.Also, since I was awarded right of occupancy, does that give me the authority to change the locks on the house or do I have to leave everything alone? Any help would be greatly appreciated.
Since we don't have privy to your decree, you need to run all of this by your attorney before you do anything that could place you in jeopardy of contempt.

