I have a custom header row made out of plain table (data) cells.
There are some problems with this setup, like user beeing able to remove that row, offseting all the data by 1 in computation etc.
I would like to add such extra header row as legit headers, but preserving default A,B,C… naming like in spreadsheet. Nested headers kind of do the trick, but requires to define ABC as well. Is it possible to append custom header row to the default one?