Trailing 37-36 with 14:07 left to play, Robert Morris scored 13 unanswered points, capped by McFadden's layup to go ahead 49-37 with 9:04 remaining.
Shane Gibson's layup with 1:27 left cut Robert Morris' lead to three, 62-59, but the Colonials made four free throws in the final minute while the Pioneers converted just one field goal to seal the victory.
Robert Morris shot just 34.6 percent (9 of 26) in the second half but made 18 free throws in the period compared to Sacred Heart's 11.
Gibson led the Pioneers (5-11, 3-2) with 27 points and six rebounds.
ESPN's Dan Dakich joins The Paul Finebaum Show to discuss the SEC's presence in the NBA Draft.
Ted Kapita was the top-rated recruit from West Virginia in the class of 2015 and recently played at DME Academy in Florida.
With the Suns drafting Tyler Ulis, they now have five guards on their roster who attended Kentucky.