32bit Deployment Type supercedence by 32bit and 64bit Deployment type?

Hi Folks,

I'm in a situation where historically an application existed only as a 32bit application. As such the existing application has 1x deployment type which has a requirement of either 32bit or 64bit. The developer has now made an x64 version available. 

Ideally the outcome we want is that:

• Where an existing deployment has been done using the legacy 32bit application on a 64bit machine it will be superceded by the 64bit version
• Where an existing deployment has been done using the legacy 32bit application on a 32bit machine it will be superceded by the 32bit version.

The issue is that the supercedence relationship between deployment types are only 1:1, so this isn't possible at a glance.

Is there a best practice or Microsoft 'supported/sanctioned' way of dealing with this scenario?

Thanks.