creating a dependent enumeration programatically

Hi All,
         I am trying to add the values to the enumeration using  (Operation Advisor):

IEnumeration<ILiteral> enumeration = (IEnumeration<ILiteral>)workItemCommon.resolveEnumeration(attribute1, monitor);
                         List<ILiteral> enumerationLiterals = enumeration.getEnumerationLiterals();
enumerationLiterals.add(i2);

My question here is : Even if i configure this enumeration as a dependent of another attribute in the process template, my code will run everytime the WI is saved. So, how to make sure that only 1 set is generated so that it will be used for later similar combinations? without adding on values over and over?

Thanks.