Think about it from the perspective of a possible benefactor. If they're being lured in with these images at all, there's clearly an emotional element to it. If they start realizing the images weren't real at all, there's a very good chance they will stop donating because you have lied to them. The crux of their support was based on falsehoods.
Personally, I'd prefer donating to an organization that isn't trying to use "sad" images to gut-punch me in the first place. There's a reason the "Arms Of An Angel" ASCPA ads are a laughingstock.
I have a feeling this will have exactly that effect of chilling donations. Because I would have this reaction. How would I know the photos are real? It’s not like I’d say no and go away, I might say “I don’t have a time right now to verify this. I’ll come back later” and then forget.
Personally, I'd prefer donating to an organization that isn't trying to use "sad" images to gut-punch me in the first place. There's a reason the "Arms Of An Angel" ASCPA ads are a laughingstock.