No. "Draft blocks " (formerly called pattern pieces) in draft mode can not be merged. “Pattern Pieces” - (formerly called details) can be merged (sort of) in Piece mode via the Union tool.
What Grace is describing is doing all your drafting in one draft block so that you can use the move tool to move (and rotate) points and curves within that block. In other words you can accomplish what the Union tool does by using the Move and Rotate tools… without encountering some of the issues the Union tool apparently still has. Not to mention, the Union tool will not mirror a Piece, so for example you can’t Join a facing to the center front of a bodice without it being upside down.