My H is a cop in MoCo and he use to do "stand bys" all the time. He would stand by the house during the removal of items and ensure he did not take anything that was not on the court order. 50% of the time there was an issue that he could quickly deescalate except for once.
He would also do "stand bys" for the exchange of the children but that was mostly done as private security. It costs about $35/hr.
I believe (this was a long time ago) there is a place in Rockville that is supervised by trained volunteer for the exchange of children. Here is a link to one... it looks like Kensington...
http://www.tacfcr.com/ it is obviously needed because they are "not taking any more cases".