Automatically "blacklist" subfolder urls from available slugs?

Hi,

I have a website that includes multiple subfolder directories for entirely different websites dedicated to different products and services that I have. My main directory is wordpress, and I add new subfolder sites all the time to the site. (e.g. http://www.mysite.com/sub-website1/).

I also write blog articles and make pages on my main website and I’ve had a couple issues of the slugs for the pages being made identical to a subfolder that already exists (e.g. a blog post with the title “Extra Service” would create the slug “extra-service” but I have a sub folder directory already created called “extra-service” on my FTP). This causes issues obviously.

I can manually fix these issues but I’d prefer something that automatically deals with this issue similar to how WordPress already deals with slugs of identical nature (automatically adds a −1, −2, etc to duplicates). Is there a plugin or hack I can do to make this happen?

Thanks!