When doing the Scottish half of the wars you should include the Welsh ally for Edward. Most of the foot was Welsh or from the Marcher lands by that stage.
Can’t be sure without the rules to hand, but I have a suspicion that the Feudal English list description mentions the origins of some elements as possibly Welsh or borders/marches already (?). If so giving the army an encumbering ally might not be required?
Having The Book to hand, IV/23 mentions that the levy infantry were unwilling or prone to desert, except for those accustomed to service against the Welsh. IV/3 (Anglo-Norman) has 1 x 3Ax (Welshry) whom it mentions were tenants of marcher lords, rather than independent Welsh, and also an option of 1 x 3Lb (South Welsh).
I expect to complete the Napoleonic's this week as both armies are in 2mm!
Irregular Miniatures 2mm are great for big battles.....have fun! And report back?
I’ve just played a 2mm ACW game using a variant on Bob Cordery's Portable Wargame rules.....extremely portable, on a 20” square gridded cloth, 10 x 10 50mm squares... great fun, very well suited to solo.