We have a customer that is using Eagle as well and would like to do the same. We have proposed writing a migration tool for them to bring in the components as virtual documents and then using the BOMs to generate virtual documents that represent the boards. The migration tool would generate the relationships between the boards and the components according to the BOMs. Also some of the boards have SW models that represent them so in these cases we will not be using a virtual document, but instead link the component virtual documents to the SW file. However, they did not bring up the point about the reference designators. I guess the question to you would be how exactly would you want the reference designator information seen or tracked. My understanding is that the relationship between the designator and the actual component lives at the board level and not at the component level. So perhaps using named BOMs of the boards where you could change the value of the designator might be the best way to go. The import tool could generate the relationships of the components and the boards then produce a named BOM and fill in the reference designators based on the Eagle BOM. That’s my first thought. I’ll be interested in seeing what others think.