Group picture (25 people) outdoors

I have a job coming in a week and a half to shoot a family reunion. It will be shot in the morning (10am) outdoors at a park / garden. Any suggestions to how to get 25 people in one picture using my 24-70L or 17-40L. I was thinking of bringing a step laddar so I can shoot from different angles.

Also, if shadows will cause a problem, would 3 fill flash setup solve it (1x 550, 2x 430)?

Thanks!

Did a wedding once and had to shoot close to 150 people in a group. Took a large ladder rather than a step ladder. Worked out great. Had the sun behind them and exposed for the shadows. They loved the result.

Though I am not Pro, I am often the Appointed Photographer. When I really want them to be happy with the results, I will fire off 3 or 4 bursts of shots, then Cut and Paste the best faces from each frame. Statically speaking, with that many people, you are not going to get them all looking at the camera, with eyes open pleasant smiles on just one click.

Rad