PrC advancement question...

[Amechra]

Would it be balanced to make it so that PrCs and dual-classing feats (Swift Hunter et al) would also advance any ACF or Racial Substitution ability that you might replace whatever they advance with?

So you could make a Swift Hunter based off of Riposte instead of Skirmish, or use Daring Outlaw to get a Fighter Feat progression on Swashbuckler by using Feat Rogue.

Or, alternatively, do something like advancing on of those abilities that replace Familiar, Animal Companion, or Special Mount through PrCs.

And I would love to do something like a Bard 7/Loremaster 10/Something 3 advancing Bardic Knack; it truly would be badass.

So, would this be balanced in your opinion?

[Mooncrow]

In general, I think that if the PrC advances the thing that the ACF replaces, it should advance the ACF as well.  That's how I play at my table, and it seems to work pretty well. 

[Empirate]

In general, yeah, but you'd have to be careful with variants that remove one aspect that's advanced with the multiclass feats AND one aspect that isn't. Probably shouldn't let both be  advanced.