Grade field dropdown in Redwood promote (Positions)

Summary:

We are currently testing our Redwood pages and have moved onto the Promote screens.

We have managed to get most the fields like for like, however when selecting a new position to promote the member of staff the 'grade' dropdown lets you select any grade you like and submit.

Currently we synchronise grades at a position leave, and as part of a promote, we would not want a manager to change a grade where a position has been selected.

We have found new positions where 'Valid grade' AND 'Entry grade' have been input, Redwood then grays out the 'Grade' field so it can not be updated (Which is what we are after)