Hello Priya,
Is this partner role belongs to Single TU?
When do you create this box? after TU creation?
if yes,
You can use a bin to create a HU (ex PACK station) and assign TU number to this HU.
For this you can use HU identification types from customizing. spro>ewm>cross process>HU>External identification types>define identification types.
Define a identification type here.
When you create a HU, update the field with TU number in detail 2 tab.
Hope it helps.
Regards,
Jobi