In previous SW version when you inserted a BOM you had the option to select multiple configurations to be displayed in that BOM.

Now all there is is a drop down box to select one individual configuration.

How can I add multiple configuration rows into my BOM like I used to in previous versions?

Old BOM property manager            New BOM property manager

as noted previously, you have the option to select multiple configs on previous version where as the right image only gives you a drop down box to select one config.