Currently, If you place a Children Display macro in a MultiExcerpt it will not display properly in the MultieExcerpt Include.
If the page with the MultiExcerpt Include on it has no children pages then it will appear blank as if there is no macro in place.
We have issue
If you use the a MultiExcerpt Fast Excerpt and MultiExcerpt Fast Include pair you can still nest the Macro. You can use either the block or inline macros to accomplish this.
You may need to change the type of include maco after your migration has been completed in order to render the include in the context of the MultiExcerpt page, which is the default behavior for MultiExcerpt Include on Server.
In Cloud, the "fast/dynamic" version of MultiExcerpt Include renders its content using the context of the page that the MultiExcerpt is on. This matches the default behavior for the MultiExcerpt Include on Server. See this document for an explanation of a fast/dynamic macro: /wiki/spaces/SUP/pages/147360348