Power Query , Transform Column of Records

Hi, I have been trying to transform a column of records by another column ; I have mangaged this as an 'addcolumn' so;

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But I cannot figure how to get to the 'outside' columns when using Table.TransformColumns,

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I have attached a workbook showing working out so far, There is an addcolumn query using the above and a query called RecordTable
which is where I've got to using transform column; so the question really is to access , in this case the 'item' column when using
Table.TransformColuimns ?

Richard.

So "I can't" is the short answer ? , thanks for taking the time to respond and I did learn a few new things while trying.

RD