Separating Combinations from Item Quantity

[Glenstorm]

Does anyone have suggestions for the following scenario:

We are hosting an event.  

We would like to offer event tickets in our shop.  Event Tickets cost $60.  

We would like to include an add on for the event tickets instead of creating a separate item. 

The Add-ons are tickets for drinks. There is one price for wine and another price for beer. But there is a discount for buying 2 of each drink ticket.

For instance 1 wine is $8, but 2 wines are $15.

I've created combinations for each of the different combinations for these drinks. 

However, I don't want the quantity of the initial item, the event ticket, to multiply the cost of the combinations.

By default, if someone buys 2 event tickets and adds two glasses of wine they should be charged $135.
    2 Event Tix                  -          $60 x 2 = $120
    1 Add-on of Wine Tix -  2 for $15x 1 = $15
    Total                             -                         = $135

The default behavior will in fact charge them $150.
    2 Event Tix                  -         $60 x 2 =  $120
    2 Add-on of Wine Tix - 2 for $15x 2 = $30
    Total                             -                       =  $150

 

Is there a way to override the default calculation?