This blurb from Hinshaw raises more questions than it answers.  Read it and try to decipher:

"A federal district court has held that absent reliance by the client of a lawyer, the lawyer’s apparent partner was not liable to the client in a legal malpractice action against the lawyer for the cost of litigation arising out of the lawyer’s allegedly negligent amendment of a trust. The issue before the court concerned whether the apparent partner, who was the lawyer’s father and whose name was on the lawyer’s letterhead, was an apparent partner of the lawyer. The court acknowledged that a partnership by estoppel might be created in such a situation under Wisconsin’s version of the Uniform Partnership Act. It consequently found that the issue was whether the required extension of credit or a change in position was met. The court held that the apparent existence of the partnership, alone, did not establish that those requirements were met without evidence of involvement of the lawyer’s father in the representation. "