It looks like you have multiple Squeezebox servers on your network. Is there a server running on „Owner-PC“?
To transfer a player from one server to another you have to click on the player (which is located on server 2) via the web interface of server 1. You will then be asked whether the player should be transferred to server 1. If you click OK, the assignment of the player changes and you should be able to synchronise all players on server 1.