Zeus, Poseidon, Iasion and Karmanor.
Zeus, Poseidon, and Iasion/Karmanor
Demeter was not married. Demeter had two consorts in Karmanor and Iasion.
Karmanor, consort of Demeter, and who purified Apollon after he killed Pytho; is in myth never said to have died. Neither is it known who his parents might have been, so there isn't any telling if he was mortal or immortal.
Demeter's husbands have been Zeus, Poseidon, Iasion and Karmanor She was never officially married though. Sadly, only two of her children shared a father. Zeus was the father
Demeter's immortal lovers were Poseidon & Zeus, her mortal lovers were Jasion, Karmanor and Mekon.
Yes, Demeter is mother of eight children. Persephone (with Zeus) Ploutos (with Iasion) Bootes/ Philomelus (with Iasion) Korybas (with Iasion) Eubouleus (with Karmanor) Khrysothemis (with Karmanor) Despoine (with Poseidon) Areion (with Poseidon) Artemis is also at times called a daughter of Demeter.
Demeter has three daughters. By Zeus, Persephone. By Poseidon, Despoinê. By Karmanor, Khrysothemis/Akakallis.
Demeter's daughters are; Persephone, by Zeus. Despoena, by Poseidon. Khrysothemis of Krete, whose father is Karmanor.
There is no "karmanorone". If you mean Karmanor: he was a demi-god hero by loving Demeter, but no parents are named for him.
Yes the children of Karmanor (Eubouleus and Khrysothemis) are usually thought to be from Demeter as no other mother is credited to their birth.
She has 8 (fathered bu zeus, poseidon, karmanor and ianios) Persephone, Queen of the Underworld, is the most famous one.