From Affinity Publisher, you can add pages from documents to your current document.
Affinity Publisher allows you to merge documents with your current document, adding all or just a selected number of specific pages at a location of your choosing within your document. This is extremely useful if you want to add a cover to a digital edition of a book, or for assembling book chapters.
To merge documents:
Do one of the following:
From the Document menu, select Add Pages from File.
Right click on a page from the Pages panel and select Add Pages from File.
You will be prompted to locate the file you wish to merge. When you have selected your file, click Open.
The Add Pages from File dialog will appear. From here, you can choose whether you wish to add all of the document's pages, or select a specific page or page range to merge. You can also select a location in your current document for the merged pages to be added to, or opt to overwrite existing pages in your document with the pages you are adding by selecting the Replace option. When you have filled in the options in the dialog, click OK.
An additional Imported Text Styles dialog will appear. If master pages and text styles are identical between the two documents, then those of the current document are used (no duplicate pages or styles will be added). If master pages differ, the incoming master pages are imported and added and will still be assigned to pages as before. If text styles with the same name have different settings you can either overwrite the current document's text style or rename the incoming style. If there is a new text style then it will be added to the document.