Write a script that swaps linked file inside main file

The objective of this script is to automate my linking, saving, exporting process. Images included.

I have a main-image.psd from which I would like to export 3 different images. On this main-image.psd file contains “hat-link,” a linked layer that contains 3 different layers, A, B, and C. Whatever I save in hat-link.psd will populate on main-image.psd. 

I don’t mind my current method which is “save layer A in hat-link.psd, return to main-image.psd, export,” then repeat that with layers B, and C. The problem with this method is that it's time consuming because my linked file has around 30 layers, not 3. So far I've been saving and exporting manually.

Is there a script I could write that says “save layer A in hat-link.psd, return to main-image.psd, export, save layer B in hat-link.psd, return to main-image.psd, export; save layer C in hat-link.psd, return to main-image.psd, export" without doing this manually?