(This Jan 31. story corrects sixth paragraph to show that mediator Shelley Chapman is a sitting, not former, U.S. bankruptcy judge) By Tom Hals and Mike Spector (Reuters) – Members of the Sackler family who own Purdue Pharma LP are nearing an agreement to boost their more than $4 billion offer to resolve sprawling opioid litigation after negotiating with states that had objected to terms of the OxyContin maker’s bankruptcy reorganization, according to a court filing. Sackler family members and states objecting to terms of Purdue’s bankruptcy reorganization are “close to an agreement in princip…