to make sure i know what you are asking…
you have a psd in a ae. you want to make modifications to the psd in photoshop and have those changes show up in ae.
yes, you can make all the changes you want to existing layers in photoshop. the changes you make in ps will show up in ae. if that ae project is open, to see the changes in the psd file, select the file in the project window and choose file>reload footage (or right click file, reload footage).
the changes should show up in any comps that use that psd.
i mentioned changes to existing layers…
if your psd was brought into ae as footage, then you can add or delete layers as much as you want. but, if your psd was brought into ae as a comp, then you will need to import in any new layers by importing the psd as footage, but selecting the layer you want to import, then bringing the new layer into the psd comp… so it can be a little tricky if you need to add layers.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW