Weddingbee boards

So, there's this girl who is the daughter of a family friend, and she and I grew up together from maybe the ages of 11 or so till about late high school.  We didn't go to high school together because we didn't live in the same town, but we spent a lot of weekends together when our parents would hang out with each other.  Towards the end of high school and as we went to college we kind of went our separate ways, and didn't talk to or see each other for about 10 years.  I still knew what was going on with her life though, because our moms are friends.

We ran into each other 3 years ago at a family function that her parents attended and spent a couple hours catching up.  Since then we kept in touch only sporadically via email, and had one telephone conversation.  We are friends on facebook but have never sent messages to each other on it.

I had decided not to invite her, or at least to hold off until I had received some RSVPs, but now I feel kind of like I should.  I don't know.  The thing is though, my wedding is less than 4 weeks away.  Would there be a nice way of inviting her so that it didn't seem like an afterthought?  I can't get away with saying "I mailed you the invitation, it must have got lost in the mail" because we don't have her address and she knows that.  So I'd need a better way to phrase it if I did invite her.  At this point would it be more rude to invite her late than not at all?

If it helps, she lives about 3 hrs away from the wedding location, but I think she frequently makes that drive so I don't believe the travel would be a huge deal.

My FI and I ran into a similar situation. And just three weeks before the wedding ended up inviting some mutual friends. We were just 100% honest and said something like, 

"O<span style="font-family: 'lucida grande', tahoma, verdana, arial, sans-serif; font-size: 13px; color: #333333;">ur wedding is coming up REALLY soon. We would LOVE for you both to come and celebrate and party with us if you are able. We apologize for not being able to invite you sooner, but we have been really tight on numbers. My parents were in town this weekend and after looking over and talking about all the details, we figured that since we'd love for you to be there (if you can), we'd suck up the awkwardness of the super late invitation."

And now they are coming!! =) Hope it works out well for you!