Multiple Import

This plugin aggregates multiple blog(s) into one
single blog. The imported blogs must be in the same WPMU installation
as the destination blog. Suitable for WordPress MU only.

How to

1. Using your favorite text editor, create a .txt file with all the
   links of the blog you wish to import. Separate each blog in new line.
   You can name it anything you want. Here’s an example.

   https://wordpress.org/blog1/
   https://wordpress.org/blog2/
   https://wordpress.org/blog3/

2. From the menu you can choose to specify categories and tags filter.
   You can have multiple filter in one line. They are comma seperated.

3. Click on import button and begin the import.