The kidnap mechanic is dumb IMO and should go away.
There are plenty of other non-playable characters they could have used, but it's frustrating to see party members you depend on go away with nothing you can do about it except fight her.
You can make it so Yenna is kidnapped. I'm not sure how many companions can be kidnapped but for me it was only Gale and Halsin. Lae'zel is the only other one i've seen mentioned getting kidnapped, so I assume having a party of those three when the scene triggers will always result in Yenna being kidnapped.
I believe this always results in her cat being killed though, which is unacceptable to me.