Limiting Number of Tickets

I posted this last week in the Online & Mobile Forum, but haven't heard anything yet so I thought IT/Admin folks might be able to help...

We're having a Family Pre-sale for our Academy Nutcracker and would like to limit the number of tickets a person can purchase to six across all four performances and two price types. I set-up Offers on the Web Pre-sale Mode of Sale for each of the perfs with a limit of 6. The Mode of Sale is accessed using a promo code and Mode of Sale Shift, but the limits aren't being enforced even within one perf/price type (i.e., I can purchase 7 adult tickets at one time for a given perf). I checked and ENFORCE_SEAT_LIMIT_FOR_ORDERS in T_DEFAULTS is set to Yes, so I'm not sure why my Offer limits aren't being enforced.

I also looked at Pricing Rules, but we're not offering a discount during the pre-sale so that didn't seem to work either (I couldn't save the rule without a discounted amount entered). We really want to limit the total purchase to six tickets across the performances/price types and orders, but at this point I'd settle for limits working within a perf. 

I'd love to hear if you've done something similar and how you accomplished it. Thanks!

Sara