Set the same key for all pages you want to be linked using alternate tag. Choose whatever you like. The key won't be visible to your visitors in any way. It just binds pages together.

This is how it will look like in the HEAD section of HTML. 

This plugin has been contributed by TransferGo. 

1. Install plugin as any other ImpressPages plugin
2. Open Pages section of admin and set the same key for all pages that have to be linked together