Selling Subs+Addons on the web from held inventory

Hello Tessitura Community,

I keep running around in circles in my head about this and I just can't figure it out.  We have a Web Subscriber MOS that has access to subscriber pricing at the package level.  We have a certain set of seats that we have in a subscription hold that we want reserved for new package sales.  We would like to give web users the ability to purchase new subscriptions out of that inventory.  Easy enough, give the website access to that hold code, right?  

The issue I'm running up against is that we also want to simultaneously allow those purchasing their subscriptions to add-on individual tickets to their newly purchased package at the performance level *but not from that same reserved subscription inventory as it would break up future full package sales*.  Since being able to buy a package requires you to have access to the underlying perfs and the hold code, they have access at the performance level as well.  I can't figure out a native way to block them from reserving addons in those held locations.  In case it matters Addons occur at a different price type than the Packages.

Does anyone have a genius solution to this problem?

Thanks in advance,

Sean