Given that Location is just another dimension, you also have the ability to filter on it and leverage our support for dimension groups in the Dimensions argument of the function:
Will this still work if we have multiple base currencies?
The docs say the LocationId parameter for SI.TURNOVER is Optional unless the company has multiple base currencies
Do I just leave the parameter empty and use the Location Group Dimension as you said?
Yes, just leave it empty and filter using the Location Group dimension. The instance I tested it on in my previous message has multiple currencies enabled, Location ID was left blank and I got the balance for the “Operation Locations” location group.