[Artas28]

Естественно, вместо моих путей прописать Ваши реальные »

@Echo Off
cls
Set "BoxIn=C:\Newfolder\FileName.txt"
Set "BoxOut=C:\Newfolder\"
Set "Delim=O"

Set "OutFile=Err.txt"
FOR /F "usebackq delims=" %%i IN ("%BoxIn%") DO Call :Out "%BoxOut%" "%%i"
pause
Exit /B 0

:Out
Set "Str=%~2"
If "%Str:~0,1%"=="%Delim%" FOR /F "delims=(" %%j IN ("%Str%") DO (
Set "OutFile=%%j"
2>nul Del "%~1\%%j"
)
>>"%~1\%OutFile%" Echo %~2
Exit /B 0

Так?