With H-shem's help, we are learning Hilchot Tzitzit with the Ben Ish Chai, Hacham Yosef Hayyim of Baghdad. The sefer is translated by Shmuel Hiley and published by Yeshivath Ahavath Shalom Publications in Jerusalem 5765/2005. He calls the names of the Chapters by the names of Parashiot, so instead of Chapter One, the first chapter is called Parashath Bereshith, Laws of Ziziyoth. Please note these are for learning purposes only. For the halacha lemaaseh, i.e. for what to do yourself please ask your own Rav.
Parashath Noah, Laws of Ziziyoth, Page 15:
6. A tallith which has fewer than four corners does not require ziziyoth; but if it has more than four corners, it does require ziziyoth. Regardless of how many corners a tallith may have, it may only have four ziziyoth, and the four corners to which they should be affixed are those furthest apart, as they are considered the true corners of the garment
One transgresses the prohibition of adding to a precept (Devarim, 4:2) if one wears a tallith to which more than four ziziyoth have been affixed.
One should avoid wearing a tallith which has more than four corners, even if it only has ziziyoth on four corners, since there are some Authorities who say that a tallith with more than four corners does not require ziziyoth at all. Even though we do not rule like those Authorities, it is still not correct to use such a tallith.
This learning should be in memory of Maran, HaRav HaGaon Ovadia Yosef, ztz'l.