Thre is a series of contadictory entries in the IGI for Robert. His wife is given as any combination of Barabar, Stover, Llewellyn, and Elizabeth. Sometimes his mother's name is Llewellyn. These are all LDS member submissions and the origin of the "data" is most dubious and is more likely to have come from WV than the IOM.
However Robert's father is consistently shown as John Looney and the parih Maughold. As there are four of Maugold John Rooney wills between 1699 and 1770, you may want to check these out at your nearest Family History center.
One, which was transcribed by Averil Roper and is on Brian Lawson's site, is dated 1770 and mentions Ballagilley. Possibly a sibling or cousin.