Exactly.
If you set the 'insp. lot level' & 'vendor' for modification in insp. plan header, every vendors have their level change history.
And you can define a next insp. level for next insp. lot (initial lot included) using transaction QDL#.
I think that you try to define one insp. plan for a material. It could be alternative solution.
Let me know if you meet any problem.
Regards