thanks for your reply.
So what if I'd like to show the child ID in the edit form that also seat in the parent page?
The parent template loads a view that checks for a child.
If the child is found the view loads the edit form whether if it isn't the view loads the create form
While in the creation form the post ID of the child doesn't exist in the edit form it exist and I'd like to display it to the user.
In this case you wouldn't be able to show the Child ID in the form itself, you will need to add the [wpv-post-id] to the view that is looking for the child post.
If you want to display the ID of the current page within the view then you must do this [wpv-post-id item= "$current_page"]