Does his saying, peace and blessings be upon him, "They are from their fathers" mean that they will follow their fathers into the Fire in the Hereafter? And how can this be reconciled with the hadiths that mention that the children of polytheists die upon natural disposition (fitra) and will be servants to the people of Paradise or among the best of people?

Perhaps the questioner is referring to the Hadith in Abu Dawud, narrated by 'Aisha (may Allah be pleased with her), who said: "I said: 'O Messenger of Allah, what about the offspring of the believers?' He said: 'They are from their fathers.' I said: 'O Messenger of Allah, without any deeds?' He said: 'Allah knows best what they would have done.' I said: 'O Messenger of Allah, then what about the offspring of the polytheists?' He said: 'They are from their fathers.' I said: 'Without any deeds?' He said: 'Allah knows best what they would have done.'" The meaning of this Hadith is that the offspring of the polytheists will share the ruling of their fathers in Hellfire. This issue is a matter of scholarly disagreement, and the various opinions on it have been compiled by Ibn 'Abd al-Barr, Ibn Hajar, al-'Ayni, and Ibn al-Qayyim. As for the Hadith narrated by Ahmad, al-Tabarani, and al-Bayhaqi: "Indeed, the best of you are the children of the polytheists," it means that they should not be killed along with their fathers if they are distinguishable, and they can embrace Islam when they grow up. It is incumbent upon students of knowledge to entrust the matter of the children of polytheists who died in the past to Allah the Almighty, and to strive for the guidance of the children of Muslims and polytheists in this era.