Also - shoot in RAW mode so that if any images aren't great, there's a chance they can be saved in post.
Agreed with the above regarding chance of unflattering shots using on camera flash BUT if it's the choice of that or underexposed/blurry photos then my choice would be to risk the flash.
Again, in post, there's always the option of black and white.
Also agreed, this is a tough one to get right because ultimately, everyone here can give advice but with no true idea of shooting conditions then it's all hypothetical. Also, not forgetting, you won't even be shooting so there's a heavy reliance on someone else who may not be the best with a camera.
Agreed with the above regarding chance of unflattering shots using on camera flash BUT if it's the choice of that or underexposed/blurry photos then my choice would be to risk the flash.
Again, in post, there's always the option of black and white.
Also agreed, this is a tough one to get right because ultimately, everyone here can give advice but with no true idea of shooting conditions then it's all hypothetical. Also, not forgetting, you won't even be shooting so there's a heavy reliance on someone else who may not be the best with a camera.