222 is not a blending agent,it's an ADHESION PROMOTER. Here is the "recomended" Dupont procedure.
Pick either Special Basecoat Blending or Tri-Coat Repair jobs.
I have "other" ways of doing this but,These are MY ways of doing it and if your interested,we'll discuss it further.
I personally would go 600 on the sanding and even a gray scuff pad after that as Chromabase won't fill for crap and IF your sanding is not GOOD,it WILL show.
Unless you still have some of the original base sprayed,It's doubtfull your "new" paint will match.Especally if they mixed a pint or such unless the jobber is VERY good at matching and even then,I doubt it.