Bismillaah.
Assalaamu 'alaykum wa rahmatullaahi wa barakaatuh.
Shaytan (Ibless) has no family. He has his soldiers from the living (i.e. jinn and the human) but from NOT the dead helping him to spread evil around the world. Impossible for him to have his followers from the dead. Also he can have his followers from the muslims to the non muslims...it is not restricted to non muslims only.
Ibless (shaytaan) made it clear when he was expelled from Jannah, Allaah said Ibless said:
'' By Your Might, I will surely mislead them all. Except, among them, Your chosen servants.'' [Surah Saad (38) 82-83]
Shaytaan said ''By Your Might and Your Majesty I will not cease from misleading Bani Aadam as long as their souls are in their bodies.''
Reported in Sahee ul-Jami (1646)
So clearly as you can see ibless can not have any followers after death.
Shaytaan has been given respite until end of time to do as he pleases, he is a test for mankind from Allaah (The All Wise). So whoever follows him will entre the fire and whoever saves himself from falling in to his trap then in sha Allaah he is saved.
Allaah (The Most High) says: ''Shaytaan has overcome them and made them forget the remembrance of Allaah. Those are the party of of Shaytaan. Unquestionably, the party of Shaytaan-they will be the losers.''
[Surah al-Mujaadilah (58):19]
Shaytaan is the one who begins the battlefield himself and positioned his throne upon water, then he sends out his allies to cause mischief on earth, to lead us astray. He is the most vehement in his misguiding of Bani Aadam.
Shaytaan does not sleep. He vowed himself to do evil, he is not fatigued by his attacks upon us at all moments. So there is no leniency upon the battlefield with him. It's a vicious battlefield between us and the shaytaan, and it will not end until Allaah establishes the Hour.
Shaytaan whispers to us to do bad, but has no power over us if we turn to Allaah. Allaah The Most High says:
''Say: ''I seek refuge with (Allaah) the Lord of mankind, The King of Mankind - The Ilah (God) of mankind, From the evil of the whispers (devil who whispers evil in the heart of men) who withdraws (from his whispering in one's heart after one remembers Allaah. [Suran An-Nas:1-4]
We should all seek refuge in Allaah from the accursed Shaytaan and seek protection with Allaah so that He preserves us.
May Allaah forgive me if I have said anything wrong.
Was-salaamu alaykum.