I am merging two custom values "0000" together with a dash, and the result
loses the leading zeros. Ex. 0001 and 0101 end up as 1-101 and I want it to
be 0001-0101. Note*The number of leading zeros changes since I have a huge
list of values, so I can't just add the 3 and 1 zero(s) needed in this
example.

using formula =(F7&"-"&G7) AND Custom Format 0000 in the two previous
columns to the function column.