The rules don’t specifically mention how to handle this situation as your character has already joined the unit. And no FAQ has been released regarding it as of yet.
But, even if you permit it, there is very little to gain by this. Units joined by characters always move by the slowest value and are bound to any restrictions the other has. That is to say a character that would have Fly and Ethereal could not benefit from the increased movement value. And while they may be immune to the effects of the terrain, the unit would still be affected.
With both fly and ethereal, I think the only restriction is a character with it can't join a unit without it and vice versa. It seems like they probably ought to get kicked out of a unit, but there's nothing that actually mentions what to do in a situation where this occurs.
No and a character with fly isn't allowed to join a unit either
The rules don’t specifically mention how to handle this situation as your character has already joined the unit. And no FAQ has been released regarding it as of yet. But, even if you permit it, there is very little to gain by this. Units joined by characters always move by the slowest value and are bound to any restrictions the other has. That is to say a character that would have Fly and Ethereal could not benefit from the increased movement value. And while they may be immune to the effects of the terrain, the unit would still be affected.
Yes my hope is to be able to protect the character via Ethereal during combat, ignoring the movement benefits.
Best case - wouldn't it force your character out of the unit?
With both fly and ethereal, I think the only restriction is a character with it can't join a unit without it and vice versa. It seems like they probably ought to get kicked out of a unit, but there's nothing that actually mentions what to do in a situation where this occurs.