I don't think the younger Nuns had any idea, they were probably told very little, and just followed orders.

I'm not sure what you mean about Mary though?

I think so too, having rewatched it last week. And Mary, she told Philomena something that wasn't true (that Michael didn't talk about her much), but did she genuinely believe that?

I think that maybe she was in denial, but maybe also Michael may not have discussed his past with his family, he did with his partner obviously. But I think, being the kind of people they were the mere mention of his past may been cause for anxiety for his adoptive parents. Mary also said that their upbringing was miserable, I wonder how true that is.