I've already replied to you in regards to sharing activity below.
www.joomlapolis.com/forum/255-developer-members-support/242306-cb-blogs-with-groupjive?limitstart=0#317570
The Share API will be implemented after I've rewrote how stream parameters are stored. Currently the stream object is passed around via session data. This makes it hard to rebuild the stream from only the activity id and know the correct parameters. The plan is to implement a backend management page for creating streams those will just be referenced by their stream id allowing the rebuilding of a stream and then activity posts will store in the database what stream they belong to so the parameters properly persist no matter the location.