"add blocks" only to certain page

hi guys,

could anyone point me to a way to assign blocks only to certain pages within the "groups" component? I want to add iframe to one of the groups, not to all of them or add different iframe to all of them. I see that group pages are dinamically generated so they will not show as individual pages in "pages" in the backend. This could possibly be a feature request, like a drop-down menu or something in case it is not there already and I haven't seen it.

I was thinking of using css and display none to hide the block, but it is not an optimal solution.

Any ideas?