We have a Review Portal case where some users require the ability to edit some of the form data.
I was told that "Phases" is how it is handle in Composer.
What is the Best Practice for handling this in Maestro?
Phase variables are not a feature in Maestro. You simply use a data field.
N.B. For reusable components what you can do in Maestro is define a field reference in the block, and link that to a common data field in the form. This does mean you need to do this binding every time you use the block.