Answer: That is a loaded question, with more than one opinion for an answer. Therefore, it is advisable not to wear such a garment, unless it is sewn closed in the folded position, whereby the new corners are the ones on which to tie the tzitzis. If one did wear it without sewing it, the tzitzis would have to be tied onto the original corners, but one would not be able to make a bracha on such a talis, because its status is questionable.
Question: If someone tied a new set of tzitzis fringes onto a talis that still had its original fringes – may the talis be worn as is? May it be worn after the original set is removed?
Answer: No and yes. It is forbidden to wear more than one set of tzitzis, by dint of the Torah’s prohibition against adding to the mitzvos. In the latter case, after the old tzitzis were removed, the lenient ruling is surprising, considering the principle we learned in our last lesson (excerpted): “there is a principle that a mitzvah object must be initially made in a kosher state to be valid.” For a reason which is more complicated than this discussion permits, that principle does not apply here.
Question: Suppose a person has a garment with four corners, but it is not a simple sheet-like piece, like a talis; it’s more like a shirt with two slits in it from the bottom up. How high up do those slits have to be in order for the garment to qualify as a four-cornered garment and be obligated in tzitzis?
Answer: The slits have to go up more than half-way, and should be clearly recognizable that they do. And by the way, half-way means from the bottom to the shoulders, not to the arm-holes!
Question: Say that a garment is rectangular – like a poncho – but one attaches the side edges to one another to make it more like a shirt. What kind of closure would it take to change its status from being a four-cornered garment to a shirt?
Answer: In addition to being closed at least half-way (see above), the closure itself would have to be secure – e.g. pins or clasps, that cannot be easily undone – in order to change the garment’s status.
Statement: We have already learned that a rounded “corner” is not a corner as far as tzitzis is concerned. (No cutting corners, OK?!)
Question: Is a four-cornered head-dress, such as kafia, obligated in tzitzis?
Answer: No. A garment which is primarily a head-dress is not obligated in tzitzis, even if it happens to cover a large portion of the torso.