Client sues attorneys for legal malpractice, and attorneys counterclaim against client for "contribution and indemnity."  When may this properly go forward?  What is "contribution" and what is "indemnity" ?

Contribution is the apportionment of  fault among joint tortfeasors.  Several contractors who each negligently damage a tenant might seek contribution among themselves. 

Indemnity is the situation in

When might an  attorney be liable to a non-client for legal malpractice?  ""The law in New York does not recognize any liability on the part of an attorney to a nonclient third party for injuries sustained as a result of an attorney’s actions in representing his client absent fraud, collusion, or a malicious or tortious