You will need the the Gift Import ID to update gift records via Import. To find the gift import ID:

1. Click Records, Gifts
2. Open the appropriate gift record
3. Select File, Properties from the menu bar

More details on this value can be found on our website at
What is the Gift Import ID or Gift Link (GFImpID, GFLink, or RGALink) and how to find and export it? (BB220184)