we use Grocery CRUD Enterprise and we had a simmilar issue with the $_POST / $_GET method.
After your suggestion we have passed our data using the $_GET method. This works perfect, but it has one disadvantage. All the data are shown in the link. (...project.php?ProjectNo_ID=4010...)
We have also tried to use $_POST and $_SESSION, but these two methods do not work in callbackAddForm or callbackAddField. Variables are in this case empty.
Prefered solution (but unfortunately not working):
Is there any way, how to pass the data from a form into AddForm without to show them in the link?