Actually, Alexander's son was Alexander IV, not II, and I doubt he was murdered by Philip Arrhidaeus. The latter was Alexander's half-brother, but history described him as being feebleminded. Apparently he ruled as a puppet-king, although no-one knows for sure exactly how feebleminded he was.

There was another supposed son, Heracles, who Alexander got from Barsine, the Persian wife of Memnon, one of Darius' Greek commanders. The conception is IIRC supposed to have taken place at Damascus, but to my knowledge we don't hear of the boy until after Alexander died, so I have my doubts about Heracles' parentage. Mind you, I am not up-to-date on Alexander, so I am not sure if what I say is the current view.