(This April 29 story refiles to change marking to marketing in 9th paragraph) By Dietrich Knauth (Reuters) – Judges on a U.S. appeals court appeared hesitant on Friday to revive a legal shield that would protect members of the Sackler family who own Purdue Pharma from lawsuits related to the prescription opioid OxyContin, a key to ending the company’s bankruptcy. During oral arguments, a three-judge panel on the 2nd U.S. Circuit Court of Appeals probed the limits of a bankruptcy judge’s authority to protect non-bankrupt parties like the wealthy Sacklers. One judge described the court’s own pas…