Hi Axel,
this requirement doesn't make sense for me, because after the second INSERT the first index you got might be wrong now. So only the index of your last INSERT will be correct.
Why do you need this index, if you have a sorted table with a unique key?
If you want to keep access to this line you can also use
INSERT wa INTO TABLE itab ASSIGNING <fs>.
or
INSERT wa INTO TABLE itab REFERENCE INTO dref.
Regards,
Klaus