Using FDT's GUI, each AIR target (iOS, Android, Desktop, Blackberry) can only be linked to it's own description.xml per project. So, conceivably, a project can only have 4 unique descriptor files active at once.
If you wish to have multiple description.xml files per target (e.g. 4 unique description.xml files only for Android), and not use ANT at all, then the best thing to do is to create separate projects per target 'flavor' and have each project inherit from a base project. Then use the launcher chain to have all the configurations go off at once (if using the ADL).
For deploying, since you have to go through the project properties anyway to redeploy an application (for release), you might as well just change the description.xml on your way to exporting the application.
