I have a requirement to write a code that update an existing lookup field. We are running sharepoint 2010. We have a content type, which is used throughout all the sites. The content type has a field called Product, which is a lookup field for all the products we have. The field also contains subproducts. For example, a product by name PR1000 has a subproduct PR1010 all in the same drop down menu. Now we want to change this grouping and separate them based on product and subproduct. I have created new field called Parent Product (PP) and Child Product(CP). I would like to programmatically update the Parent Product field with Product and Child PRoduct field with child product if any. So here is how it works; if an existing item or document has product PR1010, I would to update PP with PR1000 and CP with 1010. The problem I am having in order to start this project is the product field is part of every document library and lists and there are 1000s of items with data for product. Please help with ideas or suggestions. I am thinking of a feature event receiver, which when activated will automatically update every item with product field not empty. Thanks for your help in advance.