Planner Tab in a Shared Channel

I have just created the Planner in the parent team (to avoid an additional SP site), and used a Website tab with a link to the planner board. First to admit it is not a great workaround, particularly given I don't seem to be able to share the planner board to a shared channel group, and have to maintain access individually. (Inconvenient but manageable as we are only a small company).