Add column to inner table of a column

[Syndicate_Admin]

Hello,

I would be grateful for any tips on the following problem.
I have a table like this:

and been trying to place value in column Date into each inner table of Data column. I know that I can simply expand Data column and the Date will stay within each row. However I need to combine those two tables into one. I am using 

=Table.Combine(Custom2[Data])

as the next step, however it eliminates Date column. How can I place Date into the inner tables as a separate column that stays in place after I combine the two tables? 

Thank you.

[Syndicate_Admin]

= Table.Group(Custom2, "Date", {{"Data", each Table.Combine([Data])}})

[Syndicate_Admin]

Thank you. However I get "column 'Data' of the table wasn't found".