Since Ver 5.5, eDocPrinter PDF Pro supports merging with existing PDF by
[Append to] or [Insert Before]. When the existing PDF contains different
password security settings, users have to provide the original owner password in
order to finish the merging operations.

Since Ver 5.58, eDocPrinter PDF Pro supports PDF-Overlay. It can
be used as easily as Merge by choosing Merge by [Overlay] . In addition to this
mode, users can also assign a PDF as template for overlaying. In the simplest
case, it is equivalent to have PDF-stationary using this template PDF. Multiple
pages PDF is also allowed for overlaying. In such case, it is very similar to
print on used paper in real world. Just the result is a PDF file instead of
paper. Users can control options for overlaying in Destination property page.
When the destination page size is different from the one in template PDF, the
overlay will doing stretch fit to fill the whole page for overlay. Of course,
this function can be disabled from the options.
When the existing PDF contains different
password security settings, users have to provide the original owner password in
order to finish the overlay operations.
Since Ver 6.00, users can create layers in PDF when overlaying
the content. Though the [PDF Layer] is new concept in
PDF 1.5, it is compatible with earlier versions of Readers. Just the PDF will be viewed as no layer in earlier versions. Only Reader version supporting
"Layered PDF" feature will display layers and make users to control the visibility of layers.
eDocPrinter PDF Pro provides creating layers in an application independent way.
Users can create and add new layers from any applications. Developers can
automate the layer creation process as simple as controlling eDocPrinter PDF Pro
as before.
The option "Overlay with" provides a simple way for defining stationary as a PDF file. The template PDF can be single page or multiple pages. It shares the similar action as "Merge by [Overlay]". Just "Merge by [Overlay]" will replace the existing PDF with the new PDF. And in "Merge by [Overlay]", the new generated PDF is treated as stationary by default. Users can change the settings for "Merge by [Overlay]" and "Overlay with" by clicking the "Option" button after the option "Overlay with". Users can override settings like the fit mode, overlay or underlay ("As background"), default layer name, or etc.
When the option "Support multi-level Layer Name with delimiter /" is enabled, the layer name will be parsed with delimiter slash. For example, "/Top Level/Category II/Sample Layer" will create a layer named "Sample Layer" under the tree structure "/Top Level/Category II/". When this option is on, the layer with the same name will also be grouped as an single layer rather than creating a new layer with the same name.