FPM TREE GUIBB Master Column with dynamic fixed values

Hi experts,

I have a GUIBB Type FPM_TREE_UIBB.

Now the requirement is to create a dynamic valuehelp for the master column. So that I can change the values at any roundtrip (maybe in the get_data Method, like i can do it for every other field by changing the field catalog.

Problem is, there is no entry in the field catalog for the master column.

Anyone an idea?

Thanks and BR,

Sebastian