TB, The recipe I got was from Hodgdon's website or orange dusters website, I can't remember. Using Hodgdon's International Clays powder, 3/4 ounce of shot would not crimp well with orange dusters or claybuster wads. However, Winchester AA wads did crimp well.
20 gauge AA hulls
W209 primers
WAA20 wads
12.7 gr Hodgdon International
3/4 oz of lead shot (experimenting with 8, 8.5, and 9 shot)
Max charge for this load is 13.0 gr = 1200 fps
Velocity @ 12.0 gr = 1150 fps
I don't think you need to go any lighter than 3/4 ounce of shot. It goes bang but does not kick in a 7 lb 20 gauge. Your daughter should be able to handle the recoil. Just don't forget the ear protection. Good luck. Dan.