5 applications into 1

I have开发者_JAVA百科 5 applications that look the same, but have some nuances. I sold quite a few of each. Now I would like to create ONE application instead of all 5, and give it for free for all customers that already bought one of the 5 apps.

How do I replace the customer's old application with new one, without the need of refund, exchange etc.?

Each app in the Marketplace is identified by the package name. The version number is used to inform the user if an update is available. If you give the new app (5 in 1) the same package name as one of your existing app, and increment the version number, the users who already bought the app should be able to get new one without any trouble.
With this solution, you'll still have 5 application, with corresponding package name to your existing apps. However, it will solve the problem of users who already bought one of your app.