Suppose you have a message, and this message is signed by 100 private/public key pairs. The signatures are then aggregated into a single aggregated signature. Now, assume the only public information available is the aggregated signature, the original message, and one private/public key pair from the 100 key pairs used in creating the aggregated signature.

Is it possible to verify that this specific private/public key pair contributed to the aggregated signature, or is such verification impossible?