tanya...the best reason to switch focus even within a grant is if the science leads you in another direction. pm me if you want to "talk".
Ha, my PI told me that nobody in the long history of his lab has ever ended up doing what they proposed in their grants! I certainly have not - my current grant is supposed to be for primarily mouse work, and years later I still have not even been trained to go near the mice. You just need to justify the change in your progress report.
Tanya, that is fantastic! Getting your own fellowship is an accomplishment indeed. Well done!