Passes while in punt formation question--

[Blue37]

Hope this comes out straight.
K has nine on the LOS, four with 50-79 and five with eligible receiver numbers.
89 80 66 60 29 58 72 85 33

Are 80, 29, and 85 all ineligible, or only one of them? If only one of them, how do we determine which one?

If 89 and 33 back off before the entire team is set (assume the up-back is moving from side to side of the formation giving blocking assignments), are 80 and 85 now eligible?

Replace 85 with 79. They now have five players on the line numbered 50-79. If 89 and 33 back off the line, is 80 now eligible?