Actually, reconsidering what you said, excessively sharing your ingame IDs could lead to problems, as it could look like you're only one person (that has access to two different internet connections; it's possible, for example if you can play from home and from work), especially if all accounts use the same email address/password etc.
Just a small piece of advice (that nobody seems to listen to, but I'm going to say it anyway): Do not share your accounts if you do not want to run into problems. Use your own accounts, choose your own password, don't tell anyone, and tell your friend to change his passwords as well, so only he himself has access to them. Just to be completely sure.
