Loads & Empties

I noted in an article while back by Coker in the NG&SLG that the D&RGW always put empties at the rear of a freight on the D&RGW. Is this true!. Assuming that a pedler freight leaves the main yard bound for a distant station and has to make pickups and setouts along the way at several locations and then make a return trip that after noon; what is the criteria used. Heading south lets assume that at the first siding (Station that there are two cars to pickup and later drop off at Station D with other cars in the train. Is the train cut here with the caboose and empties left on the main while the engine and loads pickup the additional freight. At Station C there are two loads but they are destined for Station A. At Station D empties and loads are set out for transfer that are destined for transfer to another road. Are the loads and empties sorted out here into various sidings by the road engine or are they left as a string to be sorted out by the other road. The freight proceeds to our final station; Station E. At Station E the freight drops loads and empties. On the return trip with excanged loads and empties from Station E the train procees north. It will pickup additional loads and empties at Station D. I assume that the road freight will pickup cars off various sidings sort them into loads and empties and located them in the train into priorty locations. Or will the other road have the cars sort in some sort of priority mix. An example of a mixed freight would be a few cars of livestock at the front, misc loads next, tankers and them empties. Empties also being sorted into catagories. As the freight proceeds north it stops at Station B to pickup the loads that were bypassed on the trip south that were destined for Station A. Does the engine leave all loads and empties on the main and pickup the additional loads and tuck them in behind the engine or is it added somewhere in the mix based on priorities. At Station A the train is broken up. Is this by the road freight or a yard switcher (rember this branch line operations). Is this assumption correct or am I making too much out of this. Hope this is not an overload.