If I understand you correctly, you will have to insert pages before and after
your template. Open your template, Insert pages, you can put new pages anywhere
within your document.
If you are trying to combine templates, I don't think you can. You can open two
instances of Publisher and do a copy/paste. You can save text boxes and images
as Design Gallery images, they will be part of the saved templates. You will be
able to insert them from the Gallery. You can create master pages. There are
many different ways to create what you are trying to do.