Mickey, it's your lucky day: I happen to be in a good mood!
Instead of adding a prefix when importing, one can rename existing classes with a script
PROCEDURE RenameClasses; { ? Petri Sakkinen 1997 }
VAR
className, newName, firstPart, secondPart : STRING;
i, n : INTEGER;
BEGIN
FOR i:=3 TO CLASSNUM DO BEGIN
className:=CLASSLIST(i);
n := POS(' ', className);
firstPart := COPY(className, 1, n-1);
secondPart := COPY(className, n+1, LEN(className));
newName:=CONCAT(firstPart, '-', secondPart);
RENAMECLASS(className, newName);
END;
END;
RUN(RenameClasses);