I'm looking to book two one way first class award seats ATH-EWR for my brother's honeymoon (May 2021). If only one first class seat is available I'd like to book one of them in first and one in business and keep checking for additional space to open up. What are the change fees if I am able to find an additional seat in first class? Is this the plan you would recommend? Is another F seat likely to open up close in?