So if on the first day eight people lit in one Hanukkah menorah, each one lighting one candle, and the eight candles are clearly visible, then that’s fine?

You don’t actually need a Hanukkah menorah; you can light even just like that, as long as there is a shamash and it is recognizable that it serves as the shamash. With a menorah it’s simply more familiar.

The question here is whether two different people are allowed to use the same shamash not only for the lighting itself but also for benefiting from its light, so that it is clear they are not using the light of the Hanukkah candles themselves.

There is no obligation for each person to have a shamash if the candles are near the shamash; if there is other light in the room, there is no need for a shamash candle at all.

Now I thought the question is also whether, if nine people light in the same Hanukkah menorah, one of them would light with the shamash candle for the sake of the Hanukkah commandment.

In other words, you could ask whether there has to be a certain distance between the candles, but that isn’t the right question, because in a giant menorah there is a great distance between one candle and the next.

Maybe the right way to define the question is whether the very fact that many people are lighting in one Hanukkah menorah does not look like separate lightings. Of course, if someone looking from outside does not notice that this is one menorah, there would be no problem.

I think that’s what our rabbi meant in his short answer.

This weird discussion is starting to look like trolling.