reloading nginx with tons of virtual hosts

Hi guys,
I'm having some strange behaviour with nginx. I've a website which provides services across multiple third level domains (something like sitea.example.com, siteb.example.com and so on)

The file with server aliases is created dynamically and nginx reloaded with a cron job.

I noticed that a simple "reload" is not enough to tell to nginx to reload (and eventually create) the file with new aliases.

I use a simple "include" in the server section, that points to the file with aliases.

Any ideas/suggestion?

Thank you