I almost added to my post that the IP logs should support this, but I’m not so sure that they will: while ISPs will occasionally change the IP address on your connection, it remains static most of the time, but people don’t. They can now log in from anywhere using their phone, often on Wifi at a coffee shop or anywhere they happen to be, so there are probably multiple IP addresses associated with everybody’s account by now.
On the old popular PHPBB system, if you looked at someone’s profile (as a mod), it would show you their IP, and also which other users were using the same IP.