Wheeling a mandatory charger

[AntiokosIII]

A unit of lancers has one unit directly to its's front and a second just to the first (directly to front's) units's right. The lancers are close enough to have a mandatory charge against the units directly to front. may the lancers wheel at the start of the charge to hit both without spending a card, or must they spend a green card or hit only the unit to their front?
This came up in a game yesterday. It was made moot by an intercept, and I didn't want to start a dispute over a moot point, but I got curious. Would such a charge be permitted on the idea that once the charge is declared a wheel is included? Or is the only permissible target the unit that makes the charge mandatory unless a card is spent to command a charge against both? I could not find a definite answer in the rules. Thanks

[nikgaukroger]

A Forced Charge may wheel to hit units other than the one(s) that are causing it to have a Forced Charge.