I've done a couple of different captive raptor workshops as well as shooting "ambassador" birds presented at my state's annual Cranefest, and so far based on my experience it definitely pays to bring a versatile kit if you aren't sure exactly how the workshop goes and what distances the birds will be at. At one such event I mostly relied on my 200-500mm as that worked better for the distances at the time, while at another that was held in the relative darkness of a wooded area I was very happy to have my 70-200 f/2.8, as the birds were rather close and I made full use of the wider aperture to keep ISOs lower.
At each of the events I've been to, people have largely been respectful of each other and there weren't really issues with other photographers blocking your shots if you happened to bring a longer lens. If you bring a full bag of kit, you will most likely have some opportunity to swap lenses as needed. At the workshops I've done they always have some form of pavilion or dedicated area to keep your bag and additional gear, so that you can just walk back and change lenses as needed before returning to the birds. Since it sounds like you will have a mixed of flying and gloved birds, I definitely would bring flexible and versatile gear.
As Eric said, the birds will most likely have anklets and jesses for handling purposes. However this likely will not matter as your description makes it sound like they will not be on perches but rather carried by a gloved handler that you will presumably want to keep out of frame/crop out as necessary.
Below are some of the shots I've gotten previously on an eagle carried by a gloved handler. The first was taken with a 24-70 on an APS-C body and the other two were taken with a 70-200 on a full frame body. Perhaps not as exciting as observing proper wildlife, but it's always captivating to be up close and personal with birds of prey regardless. Don't forget to enjoy watching the birds with your eyes a little bit instead of always through a viewfinder.
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