As mentioned, each horse should go well as a single, flexible in both directions, knows his commands. If you have a horse already trained as a Multiple, it helps to start the singles with them. The more trained horse is accepting of the learner horse bumping them, being slower to understand.
Having two beginners makes for more confusion to start, so you need a person with trained hands as an experienced Pair driver, to be on the reins. He is more able to help the learning horses.
A single horse driver has no skills with rein handling needed for the Pair, adds MORE to the general confusion of starting a new Pair. Lessons for the Driver to learn with an experienced Pair is best. Taught WAY before starting a new Pair, so responses are more automatic to the horses. Not having to think, THEN do rein response to help or correct things.
The Single horse is having to learn a new way of doing things, what the hitching will allow in bending, rein signals. Quite different than his single driving.
Moving on up to 4s, usually is less of a change coming from the Pair. Each set of horses in the 4 is driven as a Pair. They should be INDEPENDENT of the other set of horses in responses to the reins. Leaders turn, THEN wheelers turn at the SAME point, they don’t just follow like trailer wheels behind the tow vehicle. Leaders usually do not do much pulling of the load, that can damage your wheelers in a turn! So Driver has a LOT literally, in his hands keeping things smooth and forward when driving a 4 or more of horses.
You work the horses as Pairs and 4s, so they learn how to go together. We change sides every hitching, keeps both sides of horse trained. They may have a “Best side or position” which we use for show days. Otherwise they go where they are hitched.
Leaders usually stay leaders, they have a different attitude than most wheelers. Have to be bold and FORWARD all the time. Wheelers have to be rock solid, dependable, willing to try HARD if you get stuck a bit. Wheelers are managing the WHOLE LOAD most of the CDE. Sometimes your best horses are in the Wheeler position!! The whole group and any alternate, must get along ALL THE TIME, when working. They have to learn to bend and flex, give and take the reins as asked by the Driver.
You do not drive Pairs and 4s the same way. Expectations in the Dressage or Hazards of bending, folding, speed asked, are almost 100% different. Pairs can fly thru a Hazard, rest between them. 4s have to work things very different with two folding points in the turnout. You lose time doing gates and so have make up your speed between the hazards with a Four.
Alternates for a Team of 4 should be able to work where you put them. I am sure that the Drivers work at keeping them skilled in all aspects of team work. However from our experiences, the Driver looks at his alternate and who he will be replacing. Then he may shuffle the whole Team about, to use each horse to his best ability. Driver might move a wheeler forward to Leader, change sides with him. He might put the alternate in front, bring up a wheeler who LIKES the alternate, putting the Leader back to a wheeler. That would keep both pairs of horses happy partners.
This is NOT driving Multiple horses like your Grandpa did or the Amish still do. CDE horses are a TOTALLY different kind of driving than was EVER done in the history of Driving equines. Thinking is all different for Competition goals we now expect from CDE horses.
The “name” folks have played with the members of their Team in EVERY configuration to get the best results. They know how the animals work best in all situations, with the other horses. The horses themselves are easy with changes, secure in the Team as a herd, confident in the Driver managing them. They live in a constantly changing world of travel, competitions, new hazards, situations, so they are not usually bad to deal, don’t get excited, when routines in handling stay familiar.
Big name competitors want to win, they make it as easy for horses to be happy as possible. The money invested is high, they don’t put up with much “attitude” in a Team horse, he has to fit and be adaptable to whatever is asked of him.
Not like dealing with a Single at all. The best Pairs and Fours have the time put in to make them smooth. Hours and hours with skilled hands on the reins. That gets everyone working together to be smooth, know their places well. Nothing can take the place of time spent in working together. Gimmicks and tricks of training are not going to speed anything up, might create problems for you or the horses.
Some days that time together is some hours down the road. Other days it might be 15-20 minutes if horses all give you the big “YES” answer to all your rein questions. You get all “Yes Sir” answers, then you put them away or back out in the field. You don’t work or drill the them more, when they are so good that day. So the total is 2 hours grooming, hitching and unhitching, putting stuff away. 15 minutes of driving time today, and they were WONDERFUL in your hands!!