Add custom url's automatically

In my site i have a wordpress page linked to a custom template that generates de url to show the selected information. I will show with the url’s it’s simplier to explain:

The page has the url:
http://www.formacao.com.pt/formacao/

and the custom template generates this url:
http://www.formacao.com.pt/formacao/44/excel-2013-avancado/

The 44 is the announce ID in the database and the rest is the url-slug.

So in my sitemap only the page url is shown:
http://www.formacao.com.pt/formacao/

So my question is:
How can i add the complete url to the sitemap automatically when a user submits a new announce?

I know that i can add the url manually but in hundreads of announces is hard.

https://wordpress.org/plugins/google-sitemap-generator/