VMGdb has another entity called Product that can be devlined as Franchise and Game (at least).
Sometimes I am just about to create our equivalent here with Series.
We could make the game, a Series of Release groups.
And we could make the franchise, a Series of those game Series.
Maybe someone like @CyberSkull already started this kind of stuff.
But the inconvenient of our game Series of Release groups is that we could only link release groups to it, not works, not events, etc.