How can I add an additional field in 'MB21' t-code on item level.

[muhammad_salman3]

I want to add a date field on item level on screen no. 0510.1122.png

[raymond_giuseppi]

This area (subscreen) is accounting relevant. First ask FI/CO functional on "coding block" subject.

[muhammad_salman3]

functional said they need a return date, as when a reservation is made they want to maintain a date 'return date' that when this reservation will be end and they have to give back that specific material to authorities.
and they want this date on this sub-screen .

[raymond_giuseppi]

So you could ask FI/CO for adding the field in the coding block (some Customizing will be required so it will be displayed in the subscreen) a PAI move-corresponding will then copy value from COBL to RESB (Check form kontblock_receive) Else go for modification with sscr key ☹ or divert BAdI MB_RESERVATION_BADI (*) to raise a pop-up☹

(*) The other BAdI are reserved for SAP, and the BAdI to map customer field is restricted to the BAPI...☹