Slitherine

Two units A and B charge unit C, Unit A 'blocks' a simple charge of units C by unit B, can unit B wheel away in order to still make contact? or If is unit B's charge cancelled?

The question of "wheeling away" is specifically covered by the 4th bullet, on pg 29 in the wheeling during an assault move section. In effect the answer is "no".

The two charges are deemed to be simultaneous, so whether or not one or other charging unit can fit into the space could be resolved be seeing whether the sequence in which they charge matters. Could unit B move first and then once in contact that still allows unit A to get into contact ? If the answer is no, then I suspect the space is sufficeintly cramped to only permit one charge.

It is also worth looking at the 3rd bullet in the same section which allows for units NOT to wheel if that would mean they don't end up contacting. (But, "wheeling away" still isn't permitted.)

I believe it states you can wheel as long as your center does not pass your targets center, and something about only wheeling if it brings more of your target to your front. Second one is a bit vague but I think it means if you extend the charging units front towards its target does this are cover more or less of the target of the charge, if less then you can't wheel that far.

I personally like the wheel restrictions in the other rules it allowed for some really silly charge wheels as you wove your way through and by blocking troops.