Like has been said before, it would be fine if you know the heli and fixed wing pilots that will be in attendance.
Fixed and rotary wing CAN share airspace at the same time. There are a few ways you can go about it.
One, if your field is large enough, you can have an area at the departure end of the runway for the helis, and another one at the approach end of the runway for fixed wing.
Another is to require all 3D flight to be done on the opposite side of the runway of the pilot's stations and out of the "Pattern". Then require all in attendance to fly the pattern unless they are away from the runway. Provide a "hovering only" area at a far end of the pits, away from all pit stations and spectators for those that cannot fly the pattern.
Another would be to allot certain blocks of time for airplanes and others for helicopters. Say about an hour or 2 each, alternating throughout the day.
It's all a matter of what the pilots are capable of, their attitudes toward the other type of flying, and the size of your field.
Keep us posted on what you and your club decide, and how it all turns out.
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