Replacing colors including blurs

[Blighty]

1. Create a new transparent layer below your image.

2. Make a selection slightly larger than the white star.

3. On the new transparent layer bucket fill the selection with the desired colour.

4. Change back to your image layer. Selection must remain.

5. Do Colours > Colour to Alpha. The colour below will show through.

6. Repeat for other stars with different colours on the transparent layer.