B&G pass in Render Elements would only have the B&G in it and no other objects, so would not look like any of the previous attachments :)
So you set up the render elements like attached, render once, and then save the virtual Beauty as PNG with alpha, and the Bloom and Glare pass as PNG with no alpha, and composite (all three attached). In this case I used "Screen" mode to overlay the bg pass onto the beauty.
I actually have a request I filed with devs for the b&g render element to not use the scene alpha when saving which would reduce the steps involved as you could save everything from the render elements with alpha, but the b&g would not include "scene alpha" and just "the alpha of the bloom and glare effect" (Internal ID=526830419) - but in the meantime... :)
EDIT - Posting after you got it working, but still, maybe useful for some to see it broken down :) Also wanted to add, random screengrab of Max UI was used as the background in the composite just for speed lol.