Connect Board: Subitems and Groups

Now I want to use Connect Board feature for 3 boards, I found it miss ability to select by Group, select group and it automatically include all their items selected.

Another issue is, we are working with subitems, but I can not see any option to include or let me open subitem. So we need ability to assign a item, when we click on it, it should be let me see their subitems as items themselves.