Hi,
Unfortunately no, because those are not explicitly included. When a post is not within both the parent and child category, WorPress automatically assumes there is no connection to it. (otherwise it would not be possible to exclude them in the post editor)
There might be a solution though, using a custom code + using the At least one of the selected terms should match logic. In that case, all of the child categories will be added before the search process starts, if the parent is selected.
Add this custom code to the functions.php in your theme/child theme directory (copy from line 3 only!). Before editing, please make sure to have a full site back-up just in case!