Yii2 Project versions

if you have a start template that you use as base for your projects. And in between projects you add new stuff to your base project. What would be the best way manage these changes. Lets say you have 5 active projects that are bases on different version of your base template. Would you have a different git branch for each project? Or even create I separate git repo for each project? Or what would be the best way to continue updating your base template, but still allowing the ability to switch back to or access older version if needed?

Template is just a template. Once it’s used, it’s not longer a template but your own code. At least that’s the idea for Yii templates.