Did the Greek god Pan have any siblings?

Answer 1

Yes, as any son of Hermes would be a brother of Pan. Immortal divine sons of Hermes included Hermaphroditos and Priapos (mother being Aphrodite) Pherespondos, Lykos, and Pronomos his Satyr sons by Iphthime.

Eleusis (which is sometimes female, sometimes male) by Daeira.

And of unknown mother : his daughters Angelia and Palaistra.

Answer 2

Pan's Parentage is unclear. For the most part, he is considered a son of Hermes and a nymph.

on some accounts he is the son of Zeus and Hybris.

Answer 3

He was the son of Hermes and a nymph, either Dryope or Penelope. Hermes had other children, those nymphs did not. So Pan had no full brother or sister.