I used to think about this too. Solution is real simple: Wordpad. Find your new IP, copy and paste it into Wordpad "find" option and see if it has been previously used. If not, paste it under the eB acc name you're about to sign into and done.
----------------------
EX.
eB acc name1
123.123.123.123
123.123.123.123
123.123.123.123
123.123.123.123
eB acc name2
123.123.123.123
123.123.123.123
123.123.123.123
123.123.123.123
Etc.
-----------------------
Seems crude, it is what it is and it works. Been using this method for years now telling myself in the beginning "I'll find a better way" haven't found one yet. I'm up to 10+ pages of IPs, still works like a charm. Don't forget to always check and double check you're listing the IP in the right place though. I use a USB flash drive and save the doc in there to make things easier switching to and fro accounts.
__________________
“You have to learn the rules of the game. And then you have to play better than anyone else.”
-Albert Einstein | 
Pm sent
