How to append two or mote tables from list

Hi folks,

I am trying to append 2 or more Excel tables from folder. I arrive at this point in my Power Query procedure:

I know I can click on diverting Expand arrows and get the job done. My problem though is that my tables contain varying number of columns. The columns also might appear with different names. I want all the columns and their names from all the tables be present. Therefore I am using Append to obtain combined table with all the column names in place. The following command works fine

Table.Combine(test[Transform File])

but I am loosing column Date modified. Is there a way to append these tables and keep Date modified column in place?

Would be most grateful for any hints.