This is absoloutly a huge issue for us! we have many products and product lines and when a customer submits a new form it overrides the data that is there and pushes the current to the history which is not searchable when building lists and makes it very hard for targeted marketing!
Being able to select if we want to append the property OR update the property in a workfow for example would be fantastic! I know I have seen apend somewhere I dont recall where though.