Adding new fields to OTR screen ?

Hi Experts

I want to add a new field to order based transportation request (OTR) screen to lets say "General Data" tab. Then i want to fill that field with the order interface from ECC. Did you ever try adding a new field to the order screen in TM and fill it via interface, or do you have any information about structures that i should use and exits that i should fill that field ?

Thanks..