There are serious questions being raised as to whether this discussion (Nuns in the Congo) ever went to the Vatican. The local ordinary seems to be the source of the “permission”.
I would like to know more about this case. I first heard of it 30 years ago from Richard Doerflinger over at the USCCB Office for Pro Life Activities.
My understanding-— admittedly fragmentary -— is that it was not precisely a question of permission. One does not, cannot, seek permission for a sin. They just needed a clarification of what constitutes the sin of contraception.
Makes sense to me.