You may get the results you want by going to a full helical on your current fletchings. Feathers also help in the reguard as well. I also agree that you may also get the broadheads to group with field points by moving your rest slightly. The easton tuning guide is a great refrence to help you out.
To my way of thinking you basicly have two kinds of bow tune. group tuning which gives you the very best accuracy, not always the best arrow flight. You also have paper tuning which will give you the very best arrow flight, but not always the best accuracy. The two do not always go together. What I do is paper tune at 3, 10 and 15 feet with field points. I then go to the range with my perfectly spinning broadhead tipped arrows. If they hit together out to 40 yards great, if not I will move my rest in small amounts until I get the heads grouping very close if not exactly together. When I go back and shoot the arrows through paper I useualy end up with a small tear, not the perfect bullet hole, but as long as the tear is small, and my groups are great I am happy. their have been times though when I wasn't able to get the points of impact to come together, but they were always close and consistant.

TAKE YOUR KIDS HUNTING AND YOU WON'T BE HUNTING FOR YOUR KIDS