Reusing extensions in FIM

Can anybody say, how I can make reusable extension in FIM?

I have 3 functions to replace chars (diacritics) in First Name, Last Name and Initials.

For example (part of code):

case "LASTEN":

if (csentry["LAST"].IsPresent)
  {
   string LAST = csentry["LAST"].Value;
   string LAST_EN;
   LAST_EN = Regex.Replace(LAST, "[Б]", "B");
   LAST_EN = Regex.Replace(LAST, "[Ж]", "Zh");
   LAST_EN = Regex.Replace(LAST, "[Ю]", "Yu");
   LAST_EN = Regex.Replace(LAST, "[П]", "P");

mventry["lastNameEN"].Value = LAST_EN;
                    }

I want to use this code for 3 times First Name, Last Name and Initials, how I can do it without using 3 "tables" of changing chars?

Thanks!

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