I'll add to Bill's comments on adding HBG as an extra forage. I would wait till the bulk of your smallies are 2 pounds and or HSB are 4 pounds, or larger.

Like Bill mentioned, HBG will likely steal some eggs, but any F-2 or later could be worse when it comes to nest and egg raiding. YP ribbons gone, SMB nests destroyed if many HBG offspring with GSF traits become abundant.