Hi, I need to put validation in /SCWM/TU that when an IBD is assigned to TU

Hi,
In EWM 9.5, I need to put validation in /SCWM/TU that when an Inbound Delivery is assigned to TU, for a certain party entitled, a field in TU is mandatory, else an error message should be thrown and the assignment shouldn't happen.

Please let me know if there is any BADI available for this.

Thanks in advance