You'll be all right using your same ip. Tens of thousands of players are online at any given time, many selling their accounts multiple times or engaging in RWT with gold/irems. Trust me when I say, they wont notice if an ip on an account changes once. Like another user said, it could be a bit more noticeable if the same account keeps getting a password reset, new email, over and over from different ips.
They look for repetitive patterns that seem abnormal. And if we take each account individually, a one time ip change (email/password) won't be noticed. Nor will they be sitting just looking at your ip to see of all of those accounts can be traced back to you.
They have bigger things to worry about. Also, these things and flags happen automatically.
I can't tell you how many accounts I've come in contact with, usually buying/selling and never has anything happened. Same with power levelers, etc.
You're fine. Good luck.