Supplier and Manufacturer were sued together by Hospital over a shipment of saline that reached its operating rooms, and both defendants hired Attorney for a joint defense. Each agreed to the arrangement at a meeting where Attorney went through the ways their accounts of the shipment might later diverge, and Attorney emailed both a note recording what had been agreed. Six months into discovery Manufacturer filed a cross-claim in the same action alleging that Supplier had altered the storage logs, and Supplier answered with a demand for indemnity. Both defendants wrote to Attorney the same week: "We still want one lawyer for the two of us." Attorney has gone on preparing a single defense. Must Attorney withdraw from the joint defense?