Can a person use tape to keep the TZIZIT in its proper place so that it does not slide to the edge of the corner but properly stays in its proper place? IF yes, Can it be worn with the tape in place on SHABBOS assuming no EIRUV?
Yes. One can use tape to prevent the tzitzis from sliding down (as required Shulchan Aruch O:C 11:15), and they can walk outside of the eiruv with it (as long as the tape is properly stuck).
All the best