Hi,1. For create assembly drawing. In allegro you must visibility package geometry- assembly, refdes - assembly. Then sort refdes. 2. Assembly drawing usualy must larger than dimension board outline. For scale dimension. In allegro you export ->.dxf . Then you use software AutoCad for scale (scale 2X, 3X...). Then import back allegro. 3. In allegro -> Artwork ->create assembly drawing (add subclass drawing format ...)
For your reference !!!
For item 2, this step is unecessary. You can just create a drawing blank (for the border) at the scale you need, then let the printer plot the page to fit. If you really want to scale the assembly drawing up use the Manufacture - Drafting - Create Detail, set the scale in the options menu then draw a rectangle around the items you wish to scale up. The scaled detail will be on your mouse ready to place.
You can then either set the display to show the layers on/off that you need (to cover notes, details etc) then plot (or create an artwork)....