I agree, it is cannot be done so it isn't very noticably re-touched. Selecting the leaf and using Content-aware didn't work very well.
The people are very under exposed because fill lighting wasn't used. I would re-shoot the image.
I looked a the EXIF data for the photo and saw that ISO 1600 was used, which is adding image noise to the under exposed portions of the photo, like the mom and her son.
It seems the camera was set to an auto mode which selected the high ISO setting.
The metering mode used looks to have been Matrix or Center-weighted, which is a poor choice for doing potraiture. Spot metering is better for people shots.
I agree that's a re-shoot. But I'm stuck at work and kind of bored, so what the heck. Here's a rough attempt. I copied the other hand and flipped it for a replacement. Did some white balancing as well, but this computer at work isn't calibrated so I'm not signing off on the color.