You are most welcome, and your reply was interesting.
There are Africans who specialise in communing with these spirits of the dead and have special masks for this purpose. It sounds like you are saying that their efforts are largely in vain and that the spirits have no influence on the world of the living unless God gives them a special dispensation for that. But the initiative for such an event would rest with God and not these conjurors.
Well, the problem is that spirits (generic) CAN have some influence. Demons and Holy Angels can. So their efforts might not be "in vain" meaning that nothing at all comes of them. But the problem I see with what you describe is what I mentioned before ... if people are believing, expecting spirits to do something, this is a perfect opportunity for demons to deceive them. So there might be effects, and they might well seem benign or convincing that they are the dead relatives, but ... I think it highly, highly, HIGHLY unlikely that it would ever have anything actually to do with those relatives. And if it ever did, it would be through God allowing it. And if they are not Christians, that is highly unlikely.
Yes this is my view also. This was an offence punishable by death in the Jewish theocracy.
<<<<'A man or woman who is a medium or spiritist among you must be put to death. You are to stone them; their blood will be on their own heads. Lev 20:27>>>>>
Do eastern Orthodox Christians say prayers for the dead like Catholics believing that they may yet have an effect. Is there a purgatory in Eastern Orthodoxy?
We do not believe in purgatory as defined by Catholics. Yes, we do say prayers for those who have died, because we love them and this is all we can do for them anymore. What God does with those prayers, we do not have any expectations for. We do NOT believe that our prayers can somehow "save" a person who lived and died opposed to God. It may be possible, remember the rich man in Jesus' story, who asked for a drop of water on his tongue for a moment of relief? If we pray for someone in torment, perhaps God will grant them a moment's respite or comfort. We don't know. Perhaps God will hear our prayers, knowing before the foundation of the world that we would pray them, and act in the person's life to draw them to Him. Or ... something else. We never have expectation, we just pray for them because we love them, and the rest is God's business.
God sends rather than we summon is a crucial difference. It seems to me that this desire to honour ones ancestors and to put them on a par with Moses or Elijah has no foundation in scripture. Angels are sent to minister to us but we have no examples of what this African Christian was talking about.
Yes, it is very unlikely that our beloved grandfather was on a par with Moses or Elijah. Or maybe he was ... sometimes the very simple and humble people are very close to God. But there is no reason to want to raise them up in importance. I guess I don't get that. But if we had someone close to us who was very close to God, we would know that. My great-grandmother was such a person. Still, I would not expect God to send her to visit me. I pray for her just as I pray for anyone else I love. We don't really know anyone's heart perfectly.
But you are right. The only way it would be legitimate is if God sends. And while I believe that is possible, it is VERY rare, imo. There are probably far, far more instances of people thinking it happening who are actually deceived.
Ah OK this might be a point of difference between us. That we can ask the saints to intervene on our behalf. But as you say in this case the crucial difference is that they are with God not hanging around the house they died in or their favourite rock or tree in the garden.
I know that most Protestants would not do this, because of what they have been taught. And that's fine too. We ALL have Christ to intercede for us.

But I think it is important to realize that the only way they are conscious of what happens on earth would be if God lets them be aware. They are not floating around the corner of the room watching us. There is Scriptural foundation for the awareness of Saints on what happens on earth - the martyrs ask God about it in the book of Revelation. But they know because God allows them to.
I think demonic deception is a clear fruit of such communing. Africans love to talk and they love their connections with the community and with a wider family that includes dead relatives. But there are boundaries on what constitutes a possible community and what does not.
I agree that somehow communicating with the dead is clearly forbidden. And almost certainly what they are receiving are demonic spirits.
But we DO have a strong sense of community with the Christians who have gone before us. They are alive in Christ, and are as much a part of the Church as we are - much more so in fact. And they love us, and we love them. Because they love us, they would probably be praying for us anyway. If I go to Christ, and my family is still alive, I will certainly be praying to Him for their sake, whether they ask me to or not.