It is possible to search posts from some authors, with the author IDs in url parameters.
But how implement checkboxes with all members in the search form to let user update those URL parameters?
Hello. Thank you for contacting the Toolset support.
With Toolset, you can build custom search for post type view and add custom search filters for custom fields, taxonomies and text search but there is no way to filter view result by custom frontend filter author.
You can add query filter to filter view result by post author but frontend filter is not supported.