I am using Hibernate and I am facing with a really annoying problem, when i re- generated my Business Object and mapping files because a new property o structural change or something the old files are complete overwriting, then my validation, calculated properties, my personalization like EAGER or LAZY load and all my job in the old files are lost. There is anyways to solve this problem like merge generation, or like .net Partial class (one the generated code , the second one for my personalization)