I have been giving some thought to amendments for Donnybrook for use in Late Victorian games. Some initial ideas:
No close order formation, all units loose order (within 2" of others in unit.)
Most professional soldiers using magazine fed rifles so never out of ammo. Exception of British regulars after using "mad minute" fire double dice.
British sergeants with unit allow mad minute fire and allow marksmen to get +1 on normal fire.
British colour sergeant substitutes for one elite sergeant. Same bonuses as sergeant and +1 in close combat for unit he is with.
German sergeants with unit add +1 to close combat
German Feldwebel substitutes for one elite sergeant. Same bonuses as sergeant and unit he is with can give covering fire to another that is charging.
These would be an ideal unit for nationalist volunteers, either as their own faction or as a unit in the German Empire faction.