Section 22 of Evidence Act: A Confusion Minefield

Kya yeh mere saath hi ho raha hai ya fir yeh sach mein confusion hai? Section 22 of Evidence Act is giving me gairmaans (headaches). It says that if a document has been attested by three people, then it's presumed to be genuine, but only if they're not interested parties. But what if the document is a will? Are the beneficiaries interested parties or not? And what if the attesting witnesses are their relatives? It all seems quite muddy, na? I've read it three times, but I still can't figure out the logic behind it. Does anyone else find this section confusing? Specifically, how do you interpret an attesting witness being related to the maker of the document?