Confused on why my son’s phone has 50 GB’s of storage

Hello. I have a plan with five winds and I am the account holder. I am actually sharing data with a family friend who invited me into their sharing. With this being said the other lines with my account should be using the storage we were given all together. All of the lines do share the same data except for one line. For some reason my sons phone shows that he has 50 GB of storage which we are paying for each month and it is an wanted and unneeded. How can I fix this to where he is sharing data with the other lines in our account?