There is no substitute for the hydroxylamine sulfate nor can you leave it out. It is howwever a common chemical and should be available. The IUPAC name is hydroxyazanium sulfate, CAS number 10039-54-0
Color Developing Agent (CD 4) 4-(N-Ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine sulfate CAS number 25646-77-9
The problem may be in obtaining small amounts of these chemicals.