And if the line-numbered data is more-or-less the way it looks here, then spliting on commas and combining (concatenating) the first three elements or a regex with captures nto AoAs might be a useful step one.

If the actual data looks like this excerpt, I would just do
s/,\s*WMDS/\nWMDS/;

Of course it's impossible to tell without knowing the data if comma-whitespace-WMDS in fact a good separator string to use.