Hi there,
Understood the requirements. I believe in DB you already have a table for teams, and it likely has a primary key, like id or team_id.
I believe you don't have athletes stored in the DB yet, so this is where I come in, if I understood everything correctly. I am to allow the existing team profile to be able to have athletes linked to them, with their bio, pictures and videos.
Since you already have the team profiles, I believe you already have a team public profile pages. If so, I am to add a list of athletes to them, each being listed with the main photo and name, and being a link which takes to the clicked athlete's page, which shows their main photo, name, photo gallery and video gallery.
Let me know if I understood everything correctly, or if I've left anything out. I hope the website we're working with isn't wordpress, as I don't have wp experience. If it's core PHP or CodeIgniter, and if the code is clean, then this should be an easy project.
Regards,
Julijan