I would probably advise against B list invites for the most part because it’s too likely that the person will be offended or hurt. It can easily be interpreted as rude, despite the best of intentions.
However, it definitely depends on the friend. You take a risk by doing it, but absolutely there are some people who would totally understand why they weren’t invited and would be happy to attend (or would just decline with no hard feelings if they couldn’t).
As an example, my SO actually just got a B list invite today. It’s an old friend of his from High School (he’s 29 now), and they reconnected at their 10th year reunion last year but don’t talk much. He just sent a text to my SO and his friend (both part of the same friend group from High School, they played Halo together a lot which will be relevant in a second lol):
“Hey fellas – Sorry this is so last minute, but “Sarah” just gave me the go-ahead to invite my “Halo friends” (as she says) to our wedding and I was hoping to extend you two an invite. No pressure of course, since it is only a month away, but all the details and the RSVP are online at http://www.weddingwebsite.com. Feel free to bring a guest as well, just indicate so on the RSVP. Let me know if you have any questions and hope to see you there. Cheers,”
I thought for a second about whether I should be offended on behalf of my SO (because he wouldn’t even have a thought of caring that it was B list, he just is never offended by anything lol), but then I realized that if I have to think about whether I SHOULD be offended by something it means I’m not offended lol.
Anyway, he was upfront and admitted that basically this was a B list invite, without using those words. He made it clear that he truly wanted them to come. Plus it’s just understandable that they couldn’t invite everyone they wanted to invite and so had to wait until declines came in. And my SO and his friend aren’t close to this guy anymore, so they wouldn’t have expected an invite in the first place.
We are going actually, even though it’s about a 5 hour drive away, because it will be nice to celebrate my SO’s old friend’s marriage.
Anyway, just trying to offer the perspective of someone who wasn’t at all offended/hurt by a B list invite, since you’ve already invited her. Hopefully she won’t be offended/hurt by the last minute invite.