That’s interesting.
Who does the anan sahadi apply to? Does it apply to boyfriend and girlfriend? How about to a couple that davka did a conservative wedding to avoid agunah problems (they know enough, but aren’t frum)?
Also, I’m wondering when we wouldn’t use yuchzak anyway (I feel like it applies to marriage, but don’t actually remember). I mean, if they are holding themselves out as married, then we don’t need proof that there was a kiddushin, it is yuchzak. It happens to be that the underlying kiddushin would need eidei kiyum, but we’d assume that too under yuchzak. Is there a notion that we don’t do yuchzak when we know about an underlying kiddushin that was passul? But maybe they also did a real one?
I mean, can a couple avoid yuchzak by simply pointing to one passul marriage they did?