1. Questions: What would be the difference between a Jew and non-Jew together tying tzitzis and them together shechting an animal?
Background:
A. The case by shechting is where they are both holding onto the knife when slaughtering where the Shulchan Aruch Yoreh Deah 2:11 says it is no good.
B. You need an action of a kosher shechita done by a Jew but it does not transform the animal in any way but by tzitzis the four cornered garment is transformed into a tzitzis garment and the action required to be done by a Jew is just the means to transform it into a kosher tzitzis garment.
C. Why then would it be alright if a non-Jew made the tzitzis with the Jew even if it would not work by shechting the animal?
Answer: Since what is required by shechting is a kosher action then the whole action must be done only by a Jew according to the Shulchan Aruch. But by tzitzis you just need a garment of tzitzis made by a Jew and it was made by a Jew a non-Jew was just involved as well.