Holding trains at South Station due to Red Line delays

Does the MBTA have any policy about holding commuter rail trains at South Stations if there are major delays on the Red Line?

I am not sure about South Station, but I know they do hold outbound South Acton and Fitchburg trains at Porter sometimes for 10 mins.

Is there some sort of required notice for the hold request from the T to the dispatchers to hold the trains or a required time frame(say, continued delays of over 5-15 minutes etc.)?

In most cases I don't think they are held. Besides, it might be at Amtrak's discretion.....it's their dispatcher's territory.

It is done at the request of the MBTA red line dispatcher, when there are are major service delays. Usually it is at the request of a passenger

I think quite a few people would have to make that request, if not then they will have to just catch the next one.

It is not done when service is on schedule. It has been done done to accomodate a single passenger. After all the T is about getting people around.