For the actual overriding of the page title and meta tags, you’ll need, hook into 'wp_head'
action and write your tags for meta. For page title, you’ll need to override the 'wp_title'
or 'wp_title_parts'
filter.
If you need frontend management, I would probably write the SEO data into the groupmeta DB table. Write a group extension plugin so a group admin can input the title and meta description.
Group extension codex article is here:
Group Extension API
Tie the two together and you should be able to accomplish what you want.