Are there plugins to create user group during run-time?

I would suggest that take a look at the source code of "Create custom Group" Smart Service. Re-use the same code and create an expression function. It should be a writer function that you need to create. A writer function is required if your expression function has side-effects. Then you can use the expression function in SAIL in combination with bind()

I would suggest that take a look at the source code of "Create custom Group" Smart Service. Re-use the same code and create an expression function. It should be a writer function that you need to create. A writer function is required if your expression function has side-effects. Then you can use the expression function in SAIL in combination with bind()