
Copyright laws don't work like that nor does Geni T&C's
If you don't have permission to use a photo then you can't load it to Geni.
On the Geni upload page it states "By uploading these images, you certify that you are authorised to share them"
If you were not authorised then you should not load them onto Geni
Just posting a photo online does not make it available so that anyone can just take it and use it as they see fit. There are laws as well as the terms and conditions (rules) of the sites.
In most cases to use a photo you need to get permission from the site you took it from (ie in this case the admins of the Facebook group) and from the copyright owner of the photo.
That is true providing the photo came directly from the photographer, not a photo purchased by a third party and remains in the family to the present day. I know I would not like personal photos from my private album being taken and used by others without my permission.
Geni is aware it this issue so it would be best to leave it to them to decide.
It is not up to us to debate the pros and cons of the legalities on this topic.