Last summer, I was traveling EWR-FCO in a group of 7, all in business. Just prior to the GA's starting boarding, I went up and gave the agent out group size and asked if we could all pre-board. She said no, a maximum of 3 was allowed. It was unclear whether that meant 3 additional or a total of 3, but I didn't bother finding out as we all boarded in the regular group 1 line.