A username and password (only one) is all you will ever need.
When you are creating it choose something that you frequently use like first name and last name like "bobjohnson".
Your Sports Engine user name stays with you across all Sports Engine websites, from different sports to different leagues.
To gain access from one site to another all you have to do is log-in to that site you want "ownership/editing" rights to. Once Sports Engine recognizes you then any web master can grant you access to any page you want.
Keep your Sports Engine username and password unique that you can use and remember if you jump from sport to sport or age level to age level.