Fill down Columns based on Column List

I have a table that has quite a few columns and i need to fill down only columns that contain the "RCCD" name.

So my next step was to use = Table.ColumnNames(#"Promoted Headers1") and it gives me this nice list of Column Names

After that i want only the names that conatin "RCCD" in it so i use = List.FindText(Custom7,"RCCD") and it gives me a list of the column names that i want to use to Filldown my table in the #"Promoted Headers1" step.

However when i get to the step to fill down = Table.FillDown(#"Promoted Headers1",Table.ColumnNames(#"Custom8"))......Custom8 was the preivous step.  It gives me the following error, is there another way to do this?

And heres the MCode for that sequence:

#"Promoted Headers1" = Table.PromoteHeaders(#"Transposed Table", [PromoteAllScalars=true]),
Custom7 = Table.ColumnNames(#"Promoted Headers1"),
Custom8 = List.FindText(Custom7,"RCCD"),
Custom9 = Table.FillDown(#"Promoted Headers1",Table.ColumnNames(#"Custom8")),

Any help would be great

TY