adding to a selection in a different layer

[bartonlew]

In the layer with the mask below, I had created a selection of the mailbox and added it as a new layer.  However, I neglected to select a few areas in the upper right corner of the mailbox (seen as blurs here).  Can I go back to my original layer or its copy and select those areas and add them to the top layer?  I tried to find a video about this at youtube but no luck!  Thanks.

[JJMack · Accepted solution]

Just select the areas you forgot to select then target the layer mask you added to the layer and fill the selection with white. The will add the selection to the layer mask. Howevet the layer mask you show looks like a gradient not a selection.  The layet above the laye does not have a layer mask.  So selecting the area you forgot to select in the orignal you can do a Copy + Paste to add an additional layer on top your layer stack to abdd the missing area to the top of your document. The copy could also be a copy merg if yoy want the gradient mask effect.

[bartonlew]

I want the gradient mask effect.  So should I copy the selected area to (1) the layer with the mask or (2) the top layer which just has the mailbox in it or (3) both?  Also, I researched copy merged and it says select the top layer, then hit ctrl shift alt e and that merges all layers except those turned off.  But I don't want to do that.  I want to paste the selected area into the appropriate layer(s).  Can you please tell me the exact steps for doing that?  Thank you.