Hi,
when you say I have to submit the modifications to phpbb seo do you mean any modification I make to the forums I have to submit to phpbb seo or only modifications to this mod?
thank you

Only modification to this mod, and you can of course customize the mod as you wish for yourself, as long as you keep the copyright notice, and eventually contribute to the project.

The idea is phpBB SEO stays the place where the phpBB SEO mod rewrite are released, and only the versions released here can be distributed freely.

You can include the phpBB SEO mod rewrite for example in a premodded phpBB version of yours are release it under the same conditions as far as our mods.