Mishnah Berurah — משנה ברורה

One may not - See in Magen Avraham se'if katan 3, and it seems from his words that this [that the Shulchan Aruch says that one may not take a corner with ציצית on it and sew it onto another garment because of "on the corners of their garments"] is specifically [referring to] a corner which does not have enough [material] to wrap oneself in it (But if it did have enough to wrap oneself in it, it would be permitted). And even though the gemara prohibited [sewing a corner with ציצית on it onto another garment] even if it's a cubit by a cubit, that too is because it still doesn't have enough to wrap oneself in it. But if the piece [of garment] had enough to wrap oneself in it, it is permitted to combine it with another garment, even with it's ציצית [still attached to it]. But the Ta"z in se'if katan 3 argues on this and prohibits it. And so too is it implied in the Levush and Derech Hachaim.