A method of generating a tool for merging customizations made to a first version of a software artifact when migrating to a second version includes instantiating a mapping element for each top-level element in a first code set that does not have a complementary element in a second code set; requesting and receiving merge instructions for each top-level element for which merge instructions are not provided in the corresponding mapping element; determining whether the merge instructions for each top-level element for which merge instructions are provided require that customizations be merged into the second code set; determining whether the merge instructions for each top-level element set that requires customizations to be merged are valid; requesting and receiving merge instructions for each top-level element for which the merge instructions are not valid; and storing the merge instructions received for each top-level element in the corresponding mapping element.