"[A] party is presumptively not diligent if, at the commencement of the lawsuit, the party knows or is in possession of the information that is the basis for that party's later motion to amend." Chancellor v. Pottsgrove Sch. Dist., 501 F. Supp. 2d 695, 702 (E.D. Pa. 2007); see also Pulchalski v. Franklin County, 2016 U.S. Dist. LEXIS 46221, at *5 (M.D. Pa. April 6, 2016) ("After a pleading deadline has passed, the Third Circuit requires a showing of good cause in order to amend. . . . Under this standard, 'good cause' exists when the schedule cannot reasonably be met despite the diligence of the party seeking the extension.").