How can I build an UWP release merging multiple UNITY projects (and different unity version) ?

How can I build an UWP release merging multiple UNITY projects (and different unity version) ?
I developed my game scenes using different Unity version. I have no time to update all to latest version so I’d like to merge them in a UWP project. Is it possible ? Is it a dream ?

you need to merge the projects, why cant you update your unity projects? are the versions that different? you can try exporting the levels and all you need as a packgae but it may not be supported.