異父 is read as いふ (ifu) and means different father.
いふ
ifu
いふきょうだい
half-sibling (with a different father)
いふしまい
half-sister (different father)
いじょう
strangeness
いどう
(personnel) change
いせい
isomerism
いめい
synonym (taxonomy)
いくどうおん
(saying) with one voice
いたん
heresy
ことなる
to differ
いれい
exceptional
いぎ
objection
いろん
different opinion