Associate an Inbound Delivery to the TU in Dock Appointment Scheduling

Hello,

Is there a way I can associate an Inbound Delivery to the TU in Dock Appointment Scheduling during appointment creation? Currently I do not see an option to select 'inbound delivery' under 'reference document'. A TU is getting created when the arrival at checkpoint is confirmed but no document is associated to it. Can you please advise how to resolve this issue?

Thanks in advance.