(Psi)SeveredHead
Adventurer
How about faking it?
Leomund's Trap (or maybe I'm thinking of Nystul's Magical Aura) does this so well it fools wizards. You could start with that spell, I think.
How about faking it?
I guess it would depend on the Divination.
See Invisible can be cast on another. Detect Magic and the like can't.
Scrying uses a focus that anyone can look into as the spell is being cast.
Augry, Divination, and Commune are relatively private conversations with a deity or similar power, and they may not appreciate an eavesdropper.
I could go on, but the point is that some can be shared explicitly, some can be shared implicitely, and some can't be shared at all. I personally don't see a problem with the overall arrangement,