Use split and then combine…as you already know the static text…just split with that and then join back
Str.Split({"Notice Of Change Of","Address For Service-","Instrument"},Stringsplitoptions.RemoveEmptyEntries)this give you array of strings like below
{6232452-OC1920580,GRIGORYEV,6201481-SC1511463,NACCARATO……}
If you observe what you need is joining the first and second strings…so basically get the even group and odd group of strings and join them…
Hope this idea gives you a way.happy to help if you are stuck
Cheers