To clarify multi clanning isn't illegal and more than likely never will be. At least with regards to the toribash forum as a whole, some clans don't mind it, some do, and it will likely always be up to the clan itself.
The Parrot child clan thing is an entirely different discussion, almost unrelated aside from the fact it has to do with clans tbh.
Part of me is like yeah ok, some way to check would be nice but then again there's a reason every user can't do ip checks. Some users don't want to have their information widely available, and if that's the case, aside from staff issues, who are we to give the entire community the opportunity to find out more about them. While nothing may come of getting that information, having it there could make some users uncomfortable.
I find myself thinking it should be up to a clan to properly research it's applicants, asking around and expecting honesty from applicants.
I find this issue more to be "our clan has a problem so there should be a community wide thing to solve it". Externalising and internal issue etc.
Just properly get to know your applicants I guess.