[Georgio]

Код:

@echo off
setlocal enabledelayedexpansion

set "KeyName=HKCU\Software\programma"
set "Value=parametr"
set "Domain=domain.site.com"

 (
 for /f "delims=" %%i in ('
  reg query "%KeyName%" /v "%Value%" /f "%Domain%" /d 2^>nul^| findstr /il "%Domain%"
 ') do (
  set var_1=%%i
  for %%j in (%%i) do (
   if /i "%%j"=="%Domain%" (
    set var_1=!var_1:*REG_SZ=!
    for /f "tokens=*" %%k in ("!var_1:%Domain%=*.%Domain%!") do (
     reg add "%KeyName%" /v "%Value%" /d "%%k" /f>nul
     )
    )
   )
  )
 )|| (
 for /f "delims=" %%i in ('
  reg query "%KeyName%" /v "%Value%" 2^>nul^| findstr /ilc:"%Value%"
 ') do (
  set var_1=%%i
  for %%j in (%%i) do (
   set var_2=%%j
   )
  if /i !var_2!==REG_SZ (
   reg add "%KeyName%" /v "%Value%" /d "*.%Domain%" /f>nul
   ) else (
   for /f "tokens=*" %%j in ("!var_1:*REG_SZ=!") do (
    reg add "%KeyName%" /v "%Value%" /d "%%j;*.%Domain%" /f>nul
    )
   )
  )
 )

endlocal
exit /b