If you could take some additional photos, I think a longer view (showing all of the blocks) would be more helpful in assessing both the original and replacement fabrics. The photo with the pink doesn't show the blue or much of the green, so we're not seeing it in context. Imo, the contrast is better with the pink, and I don't think the yellow has the right 'weight' to go with the other fabrics.
I don't think the applique idea would work, because the yellow is very light and will look different with the pink behind it than the yellow without the pink behind it.
Edit
I like it with the pink; I think that fabric goes well with the others.
Last edited by joe'smom; 08-07-2016 at 05:19 AM.