Summarize Multiple Values from Different Table within either of Table - File Attached

Hi biengineer ,

According to your description, here are my steps you can follow as a solution.

(1) My test data is the same as yours.

(2) We can create a table.

Table =
GENERATE (
    SUMMARIZE ( 'A', 'A'[Machine Name], 'A'[Operation], 'A'[Time] ),
    SELECTCOLUMNS (
        RELATEDTABLE ( 'B' ),
        "Item", 'B'[Item],
        "Mcss", 'B'[Mcss],
        "Quantity", 'B'[Quantity]
    )
)

(3) Then the result is as follows.

Please refer to the following document for more information.

 Summarizing values from different tables - Microsoft Power BI Community

Best Regards,

Neeko Tang

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