The longer a person has been dead, the harder it becomes for them to appear in the dreams of the living.
But as long as one person can dream of them...
then they can invade that person's dreams.
In the Pantheon, after wearing the Dream of Void for three months, Mark had invaded many people's dreams, but only a few of them were truly useful for a "Reclamation of Bones" battle:
Tongchen, the unpredictable wanderer between sleep and wakefulness, the Snow Demon, Zhang Haoyun, Mel—and including Zhou Shou, Bai Ling, and Midel.
Mel was an unexpected joy, Mark hadn't even thought that Mel would care so much about his close friend.
To the extent of having "dreams at night."
Perhaps it was because his friend had revealed his special nature before they parted?
But all this was unimportant. What mattered was that Mel was the medium, the bridge, the key to connecting everyone to the place where the bones lay.
In the dream, Mark told them: