Okay, so I totally lied when I said I would only do Rick Riordan's original characters as dollifies, I should have known myself better... Anyway, here's Apollo's immortal kids (via mythology). Of course parentage can be disputed but these ones are at least some of the time seen as Apollo's kids.
Past Dollify Characters:
Apollo Cabin — Greek
Big 3 Kids
Demeter/Ceres
Aphrodite/Venus
Athena & Dionysus/Bacchus
Hecate & Apollo & Emmie
Apollo's Immortal Children + his godly form
Apollo: god of light, music and song, poetry, prophecy and divination, logic and reason, truth, healing and disease, medicine, averting evil, punishing the wicked, archery, herding, civilization, building cities and fortification, ritual purification, young men, youth, the sun
Asclepius: god of medicine
Aristaeus: god of rural handicrafts, shepherds, cheesemaking, bee-keeping, honey, honey-mead, olive-growing, oil-milling, hunting, Etesian winds
Hymenaeus: god of weddings, marriage ceremonies, wedding hymns
Ialemus: god of funeral hymns, sad songs
Kephiso|Nêtê: a Muse Apollonide, lowest note of the lyre
Apollonis|Mêsê: a Muse Apollonide, middle note of the lyre
Borysthenis|Hypatê: a Muse Apollonide, highest note of the lyre
Chariclo: wife of Chiron, foster-mother of heroes