You need to hire an attorney to explain all of this. If there has been no change to the original custody order, then everyone has to follow the terms of the Order regardless of what you both have been doing since then. You should bring the original custody order to court and if it hasn't been changed by another court order, then the original order controls the situation.
I am not sure why the police would be involved in a situation where a parent has the children only 45 minutes beyond what the Order says but the police only know what the complaining person says so he could have told the police anything. A lawyer can find out what is really going on.
For the same reason you can't keep the kids beyond 6:30, your ex has to follow the Order also. If he withheld your daughter, then he is interfering with your custody/access time.
A lawyer can explain the best way to handle this. You may need another custody order to clarify the holiday visitation and new weekend schedule.