Right now, when I model one object, the change [to others] is visible only after you go back to Object mode…
Can you see the changes in real time?
Cheers,
P
Linked duplicates in a scene or linked objects in other blend files ?
If you edit a linked duplicate you should see all the other linked objects also change at the same time.
Show us what you see if that is not the case
From my experience… If the objects are just plain meshes the changes are realtime. If either object has modifiers then the changes aren’t updated until you leave edit mode.