Making a Pricing Rules do Double Duty?

Hey there,

We want to use a pricing rule, triggered by a source code, to provide a volume discount via the web. Ideally, when a patron enters the code and puts 6+ seats in their cart, a group price type will become available. Both criteria have to be met. 

We're running into trouble because the price type has to exist in web MOS to be available to the pricing rule, but it has to be covered up by an offer so as not to be publicly available. But when the patron enters the code, the price type is getting unlocked by the offer before the pricing rule can kick in, without the additional requirement of 6+ tickets. 

Is there a way to make the pricing rule do both?

(Note: we can use the pricing rule to do a $ discount instead of a price type change, however that causes problems for reporting - a price type change is ideal.)

Thanks for any advice!