I have created a calculated field ("DifferenzTage") in C# code...and I can display this field as a column in the grid of a page setting the Property to "DifferenzTage"
Usually calculated fields are read-only and for display purposes. Why do you need to edit this calculated field? How you are going to submit it to the database?
I would like to display this field as information for the user in that edit page (not for edit and save to the database).
But this is not super important, if there is an easy how to do it then it would be nice.