First a comment: I see no reason why 1 user needs to access the files of another user through their home.
If you want to do this in a correct way you should create space on the disk for another "data" directory. Set this directory up with a "group". And you give access to this directory to all users by adding them to this "group" so they can put documents in there they want to share. That way you can keep their home their home. It also plans for the future: new users added to the system need to be added to this "group" and they have the same directory on the system to put files in there to share.
But if you really want 1 user to be able to access another users home add that user to the group of the other user. You can add an existing user to an existing group with:
usermod -a -G {group} {user}
where {group} will be the name of the user you want {user} to access. Mind though that this opens up everything this users owns and {user} can do anything to this persons home. Including deleting it.