(create a 'valley of content' -i.e. a few posts that lead of to whatever you are promoting, and then after words a few posts that point people back to what you just promoted, so that you are targeting your members on both side of the valley, if that makes sense).
This actually does make sense. You create 3~5 posts to promote your product and spread them out, release them a little bit slower to create a "lull" or valley in information. People who are accustomed to reading your posts, start to "anticipate" the next posts. When you create the new releases, you will have another 5~6 posts released closer together, ramping up the valley wall, and climbing up the mountain, all while pointing back to the products you promoted in the valley.
I also understand the desire to keep UGC in front of groups. Read the room, who interacts with what, and ensure that this type of content stays in front of the group. This in turn leads to active members who will automatically read whatever comes out.
I have pulled up Dave Smith. Thanks for the lead and information.
MrDon