Responsive Posts Carousel also comes with Multisite support. You can display posts from your child sites to the main site using the attribute multisite and providing the site IDs separated by commas.

Example:

[wcp-carousel id="767" order="DESC" orderby="date" multisite="1,2,3,4" count="2"]

Above shortcode will display 2 recent posts from the sites 1,2,3 and 4.