How to set owner (and guests) of a newly created board

I am now able to create a board from my Wordpress website, it nicely checks if the board already exists and if not it creates the board. It also shows invited guests.

The owner of the board created is always set to the current account admin. How do I set the board ownership to another team member, using the V2 API. I miss the ability to give the board owner id in the create_board mutation.

Also, I need to invite guest users to the newly created board. I do not see how to do this in the V2 API.