Dynamically rearrange rows into one Header column in Power Query

Hello, i have been looking for a viable solution quite some time but unfortunately did not find something appropriate so I have to come and ask you guys.

The situation is as follows - I have a table which does always have quite the same layout with the only difference that my table headers are located on a different Row starting with Column J and from Column J on i can have variable amount of Column-Headers because they are representing Inventory amounts of Calendar-Weeks - so for illustriation it looks sometihing like following

Now as i mentioned - it may be that in other tables i will have not 4 but 8 Calendar week columns instead! I am looking for a dynamical way in Power Query to "unify" the first 2 Rows into ONE HEADER COLUMN indifferent if it will be 4 or 8 or "x" columns representing calendar weeks! 

The end result should be something like this

I hope you understand my issue - if there is anything else i could help you with please let me know!

Thanks a lot for your appreciated help!!!