Is there a to design a schematic in eagle and extend it to another? So if you change one schematic it will reflect into another.

Example: I have many designs that use the same power supply. Is there a way to connect all those schematic designs to one power supply schematic so once the power supply is edited it would reflect on all the other designs?

 

I think it is not possible. But what you could do, if the psu has the same layout in all the versions, simply copy-paste the finished psu layout into the child board. Not too elegant and could be prone to mistakes because you need to loose the back-annotation to do it, but it should work.

 

I 'm pretty sure you can import a schematic into an Eagle project, and place it into a different sheet so that it's not in your way.

Not sure if that's available in the free version, though.