In Tabular models you can only have one active relationship between two tables. But you can have multiple inactive ones. In the image below you can see how the active relations are marked with a solid line. And then inactive ones are marked as dotted lines.

So how do you use your inactive ones?

I start with a basic query that gives me the sales per year. Because I did not specify a relationsship the active relationship is used. In this case the order date.

EVALUATE
 (
    ADDCOLUMNS (
        VALUES ( 'Date'[Calendar Year] ),
        "Total sales", 'Internet Sales'[Internet Total Sales]
    )
)

And the result

So if I want to use an inactive relationship too I need to use the USERELATIONSHIP function. Below is an example on how to get both sales per order year and sales per shipment year in the same query.

DEFINE
    MEASURE 'Internet Sales'[Total Sales By ShipmentDate] =
        CALCULATE (
            'Internet Sales'[Internet Total Sales],
            USERELATIONSHIP ( 'Internet Sales'[ShipDateKey], 'Date'[DateKey] )
        )
EVALUATE
 (
    ADDCOLUMNS (
        VALUES ( 'Date'[Calendar Year] ),
        "Total sales", 'Internet Sales'[Internet Total Sales],
        "Total sales by ShipmentDate", 'Internet Sales'[Total Sales By ShipmentDate]
    )
)

And the result will look like this