offset keyframe and layers with same value

Hi everyone, 

Does anyone knows if there is a way to offset layers and keyframe with the same value?

I explain : sometimes, when you need to add more time at a certain point of a composition you need to push further some layer blocks AND also only push some keyframes on a layer (most of the time this layer is my camera for example).

As you cannot select and push layers and keyframes selected at the same time here is why i ask.

I can do it manually with two selection steps but it can lead to mistakes in my count of keyframes to add. 

And also as it is a matter of timing, i need to try and see with more ease. 

I've send a visual example if it's not clear. 

Thanks