Hi manish
The only solution that occurs me is to directly change the net weight and gross weight in VBRP table using SE16 and “EDIT mode (I think that in VBRK there’s no weight fields) .
After that you should be able to change the posting date in billing documents and no dumps shoud occurs.
Note that this is a risky solution. If possible, you should test it first in a test environment.
Regards