I have checked the BADI - BADI_LE_SHIPMENT , AT_SAVE method and tried using 'WS_DELIVERY_UPDATE' function module in it.
But the vbkok structure in it doesn't have any field corresponding to Billing date.
Generally, in VL02 ,when we update planned GI date then Billing date gets updated automatically in LIKP.
And if we change the Loading start date in VT02n(shipping) , planned GI date gets updated in LIKP.
Requirement is that billing date should also get updated when planned GI date changes in VT02.
Please respond if anyone knows the solution and please let me know if any further details are required.