Distributing multiple versions of an app within a single Windows Store app

Question

The company I work for creates Point Of Sale (POS) software using Software As A Service (SAAS), so we host our clients' databases.  We do not force all of our clients to all be on the same version of our software; i.e. some clients are on version 3,
others v4, others v5, etc.  As you would expect, the database schema for each of these versions is different, so each of these clients also use a different version of our client-side app.
We are looking at making a Windows Store app that acts as a light-weight POS app that clients can use to sell their products.  The problem is, we will require having multiple versions of our Windows Store app in production; the version of the app that
the client uses must correspond to their database version.  We were initially hoping to have our Windows Store app detect which version of the app the client should be using, and then automatically update itself to the correct version, but
were told on this post that it violates the Windows Store certification criteria, so that's not an option.
It has been suggested that we put multiple apps into the Store; one for each version of our software. We really don't want to do this though, as when we upgrade a client's database from one version to the next it would require that they uninstall their current
app and install the newer versions app, causing them to lose all of their custom settings. We would like the updates to remain as transparent to the end users as possible; the store clerk shouldn't need to worry about which version their database is on so
they know which app to download from the Store.
As a possible workaround, is it ok for us to package all 3 versions of our app into a single Windows Store app, and then just have the app check at runtime which version it should run?  I assume that this is alright, since we will not be downloading
any other code or installing any software/apps, as was the case with our original solution that violates the certification criteria.  Essentially we would just have 3 different classes and determine at run-time which classes code we should run. 
I know that this solution isn't ideal, as it means our app will be 3 times larger than it needs to be, and that an update to any one of the 3 versions of our software will require an update to the Store app (so potentially users may download a new version
of the Store app, even though it doesn't have any changes for the particular code version (i.e. class) that they will use), but it's one of the best alternatives we have come up with.  I just want to check that this solution doesn't also violate any certification
criteria before we go down this road.
If this is not allowed then our only other alternative might be to go with sideloading (as
I discuss on this thread) and avoid using the Windows Store all together, but we would prefer to use the Store if possible as it eliminates a lot of overhead that we would have to deal with if we use sideloading.
Any insights or suggestions that you can give are appreciated. Thanks!
- Dan - "Can't never could do anything"

Answer 1

Hey Mr_bigworlds, thanks for the reply.  The moderator on this post actually told me that this
would be a better forum for my inquiries.  I agree that there may be another forum better suited for this question (there are so many that I don't know about), but since this relates to Windows Store certification criteria, I don't think the Windows Desktop
Development forums are the place for it.
- Dan - "Can't never could do anything"