Thanks all. It sounds like for it to work like I think it needs to, the post will need need to use the group container. So I need to get a list of all groups that the user is a member of when they are creating a blog post, and then save the post such that it's owning container is the selected group. Access level and group will always be the same I think - no need to make this needlessly complicated. The main thing I think is that this is a significant amount of work for a relatively small change in user workflow, so there is a question about whether it's worth the effort. There are issues also with Elgg's sucky handling of image and other multi-media embedding as well...

Thanks Juho for the code snippet too - that's really helpful.

@ammienoot Maybe this could help.

http://community.elgg.org/plugins/1211419/0.5/containers

There are issues also with Elgg's sucky handling of image and other multi-media embedding as well...

That sounds like a nice discussion all its own. :)