Help with query string home page

Hello! I have space for X front page enhanced listings on the home page, but as there are not always exactly X of them it sometimes looks a bit ugly. I would like to write a query string to use instead of the basic sample string “meta_key=frontpage&meta_value=yes”. I would like the string to pull all the front page enhanced listings and IF there are less than X of them, I would like for it to pull random listings that are NOT front page enhanced until all the spaces are filled up. Are there any helpful programmers out there? This goes beyond my coding knowledge 🙂 Cheers!