Well I thought about making it possible to connect them with Moria Orcs and only them, therefore not creating as many duplicate objects but only 3.
On the other hand I could also imagine the drummer directly being surrounded by swordsmen after being recruited. If that would be the case, I would imagine that they would have the same upgrades as usual swordsmen except for the banner carrier since the drummer would function as such. Also he could switch between two modes, 1. "engage" which would make him directly attack enemies and 2. "keeping distance", which would make and his bataillon him stop at a distance when targetting an enemy, same as archers do (could be done via giving him range attacks that deal 0 damage). Also yes in that case I'd connect the hordes life to the drummer and put the drummer not at the back line, but in the center of the horde.
Treating those 2 methods differently makes sense in my opionion since the first case connects the drummer to the horde but still keeps them seperated in a sense, while the second method would merge them into one drummer horde.