Meaning of the Sanskrit Word: pitrbhih

  pitṛbhiḥ—by the parental guardians    SB 1.12.31
  pitṛbhiḥ—along with the residents of Pitṛloka    SB 1.15.49
  pitṛbhiḥ—by the Pitās    SB 4.6.8
  pitṛbhiḥ—by the forefathers, the father and grandfather    SB 4.8.37
  pitṛbhiḥ—by forefathers    SB 4.12.26
  pitṛbhiḥ—with your forefathers    SB 7.10.18

Can't find any compound Sanskrit words containing pitrbhih.