Here's the mentality to this setup. The BGA pads will NOT be the pin on the decal, the vias will be. The BGA pads (& connecting tracks) will instead be associated copper to their corressponding via. This way your BGA decal will be completely faned out when you place it in your design. This method may also require you to add soldermask & paste graphics/shapes (if necessary) to the BGA pads. I hope this info helps.
You can use PADS Router to fanout all pins on the BGA. Also unused pins.
Use 'Edit > Properties > Fanout tab'
Enable both 'Plane Nets', Signal nets' and 'unused nets'
Use the router fanout tool. Adding vias in a PCB Decal eliminates the flexibility you will need when routng the board, it creates vias for pins you will not need, adds ccomplexity to CAM output.... Fan out the BGA just like you would fan out any other SMD device, using the router fanout tool that was made just for this task. Or, if you want to do it manually, use the "E" modeless command to set the route end mode to "Add Via". Start routing from the pad, <CTRL> click drops a via.
Thanks. Learned how to do this over the (long) weekend.
Thanks Pete. Learned how to do this yesterday. Learning more; still not intuitive.