Engine consists with Dynamic/non Dynamic mix of units

A question for you professional railroaders out there.
In this picture from rrpicturearchives.net the lead and trailing units are dynamic brake equipped. The middle unit does not have dynamic brakes. Can the engineer use the dynamics because of the middle engine not having it? And if the engineer can how does the middle unit react when the other 2 are using theirs.
http://www.rrpicturearchives.net/showPi ... ?id=553212" onclick="window.open(this.href);return false;

You can use dynamic on operable units - the middle/non-equipped unit just won't do anything but idle when you switch to braking.

If the lead locomotive doesn't have dynamic brakes or they are inoperative, the entire consist will not have any dynamic braking.

Sometimes just because all units in the consist have dynamic brakes, it doesn't mean they are all operating. sometimes they would cause too much buff force in the train. Railroads have rules governing the number of powered axles, and dynamic brake axles. Often the numbers are based on the topography of the line. A staight line wouldn't be as restrictive as a curvy line.

Most engines have cut outs for excess dynamic brakes. Some have a position on the isolation switch so the unit will idle in power, but run in dynamic brake.