Hi Grace, this is possible. I don't see that you're limiting this in your settings. When a player has chosen a date, they can select additional dates to register for. Please reach out to our support team if you have further questions 

Hi Julie- I looked at your Organization's settings. In Settings > General you have your Organization's Start Day of the Week set to Tuesday. If you change this to Sunday/Monday it will do what you're asking. 

Settings > General