I'm currently organising a board game night. This is an iteration of a weekly board game night amongst a rather loose group of friends, but this one is something of a bigger deal: it's happening at a friend's place on the weekend, instead of at uni on a weeknight. There might be drinking, and partying, and other things we don't normally do.

The friend who is hosting the event doesn't make it to the board games much any more, but can do weekends, so he offered to host it instead since nobody else really had the space to do so. However, people perceive it to be my event, for a few reasons: I'm the one with the board game collection, I've been agitating to do this for a while, and it's something of a farewell for me, since I'll be leaving the uni in a month.

This friend who's hosting, without asking/consulting with me, invited another person to play games. This person is an old friend of his, and something of a new friend of mine. I have no issues with this person coming to games; on the contrary, he's a pleasant guy and I think he'll be a good addition to the group.

But, this guy sent a message via a group chat, expressing gratitude for my thinking to ask him. I want him to feel welcome, but I don't want to be dishonest about the reason for him being invited. I don't really want to take undue credit, especially when this group chat contains our mutual friend who really invited him. All the options I could think of just sounded like I was trying to make him feel unwelcome.

Is there anything I could say that makes it absolutely clear that he is very welcome to come, but that I was not the person to invite him?