If the content of another Word document is related to content of the Word document that you can work on, you can embed the text of that document into the current document that you are editing. To do this, you need to follow a few simple steps.
First, open the Word document to which you want to add content or embed another Word document.
Then go to the team "Text" of the tab "Introduction" and click the down arrow next to the option "Object".

You will see a drop-down menu. There are two options to choose from here: "Object" and “Text from file”.
Object: Incorporates an object such as a Word document or a graph Excel
Text from a file: Inserts text from another file into the Word document
The choice “Text from file” is essentially a faster way to copy and paste another's content file in this.
Try it by clicking on the option “Text from file” in the drop-down menu.

This will open the File Explorer (Finder in Poppy). Find the file from which you want to copy the text, select it, and then click "Introduction".

The contents of this Word document will now appear in the current Word document. This works well if there is not much content in the other Word document, but if there is, embedding it may be a better option.
Back to the drop-down menu “Object” (Insert> Text group> Object) click "Object".

The window will appear "Object". Select the tab "Create from file" and then click "Search". The choice "Create from file" will appear as a button in the lower left corner of the Mac window.

You will see File Explorer (Finder on Mac). Find the file you want to embed, select it, and then click "Introduction".

The file path of the selected file will now be displayed in the text box next to "Search". Now, you need to decide how you want to insert the object. You have two options:
Link to file: Inserts the contents of the selected file into the Word document and creates a link back to the source file. Changes made to the source file will be reflected in your document. By his choice "Link to file", the contents of the other file will be inserted into a text box.
Appear as an icon: Inserts an icon to indicate to the reader that there is a built-in object. This is ideal when space saving is required.
We will test both options in this example.

The file will be embedded in the Word document. Double-clicking the icon will open the second Word file.
A warning with this method is moving the source file that will break the link of the embedded object. For this reason, the Microsoft prevents you from moving the source file to a different location. If you try to do so, you will receive the following message:

Finally, if you need to move the source file to another location, you need to remove the built-in link, move the source file, and then reinstall the file by following the steps above.
Source: howtogeek.com