To convert layer(s) to an editable smart object:
- In the Layers palette, hide unnecessary layers. To convert just one layer, [Alt]-click its "eye" pictogram.
(On this screenshot, the layers "Background" and "Smart" are prepared for conversion.)
- In the Effects palette, double-click the "Editable Object" pictogram.
- It opens the "Save As" dialog. Choose destination folder and save the exported layers as PSD file. For example, let's name it "so_source.psd".
- Now the action opens "Place" dialog. Select the smart object source (so_source.psd) and click "Place".
- The imported PSD appears in your document window. If necessary, adjust its size and position. Then click the "ok" button (see example) or press the the [Enter] key to confirm placement.
As result, you have a layered smart object in your document and source PSD file on your disk. Now if you decide to edit the smart object's contents, either play the Edit Smart Object action or use this algorithm.