How do you have them based at the moment? To quote a bit of the Sharp Practice 2 rulebook: "Our ordinary figures operate in Groups. A Group will be between six and ten figures for regular troops, and twelve figures for Irregular or Tribal forces."
As an example of French "Peninsular War" troops, line infantry come in 8s, voltigeur skirmishers in 6s and cavalry of all types in 8s.
And you will only need skirmishers if you want to field some skirmishers. The rules allow you considerable latitude in building the force that you put on the table but also provide examples of army lists, eg: French Regulars up until 1812 might be four groups of 8 line infantry and two groups of 6 voltigeurs.