With the latest release, mabl now supports branching tests and reusable flows. You can create branches, save tests to them, run the branched tests, and add them to plans. All without impacting your regular plan runs. Then when everything looks good, or when the code your testing is deployed, you can merge the tests in mabl to make them available broadly.
For more detail on working with branches, see the help docs
Branches and Plans
Plans are not branched but they are branch aware. All plans currently run off of the default master branch where tests edits are saved to by default. This means the plan will always run the latest version of the test merged to master. And if a test does not have a version on master yet, you can still add it to the plans you want it to end up in and the plan will skip it by default.