Selection of boosted HQ would be improved by manual control.
For example, the screenshot from a recent online game shows three German HQs, Von Leeb, rating 7; Rommel, rating 9; and Von Manstein, rating 10. Von Leeb is located in Ulyanovsk which has a supply level of 5. Von Manstein is located three hexes to the east of Von Leeb. Rommel is located two hexes south of Von Leeb.
According to the manual, higher rated HQs are boosted by lower rated HQs. However, only one HQ can be boosted.
Since Von Leeb is the lowest rated HQ and has the best supply, I was hoping that Von Leeb would boost Von Manstein, which is the highest rated HQ and closest to the front. But the AI chose Rommel to be boosted, leaving Von Manstein and the units at the front at low supply, ouch.
Supply is a critical aspect of the game, affecting both movement and combat. I think the game would be improved by allowing manual control of the selection of which HQ is boosted.