The artist who hosts the room and invited the other artist will receive all Fan-donated Love sent to them. By hosting the Jam Session, you're inviting another artist to be present in your room; and since it's still your room, all donated Stickers are yours.
The guest artist's live stream will not be listed on the Sessions landing page, as the guest is part of the host’s stream. Artists that are guests are unable to receive Stickers for themselves.
For a full step-by-step on how to use this feature, please check the Help Article: How can I jam with another artist?.