Invite Etiquette- High school couple?

MKM2014

My wedding is coming up (Aug 9! Getting close!) & we will be ordering our invites soon (like really soon- within a week). We are paying to have the envelopes addressed as well.

I have a 17 year old cousin who is a Junior in high school and lives with his parents. As I understand, children 18 & under who live at home can be included on their parents invites? However, this cousin has been in a relationship for about a year with a girl we see regularly- she comes to pretty much all the family events (Christmas/all the birthday etc.). So, I see her about once a month and the family really likes her so even though they're a younger couple I would like to invite her.

In this case, would I send a separate invite addressed to both of them to the my Aunt/Uncles home? It seems a little weird to add her name to the envelope with the children since she is not a child in the home. I see my Aunt/Uncle very regularly and they have been involved in helping with wedding planning etc. so I can definitely just "make it be known" that I would like her to attend as well without worrying about invite particulars.

This whole formal invite etiquette land is fairly new to me

Just wondering what you all would do!

manateehugger

If you plan on treating you cousin like an adult guest and inviting the girlfriend, I would go ahead and just send them a separate invite to his parent's house. 

I'm sure they will appreciate the gesture!

VulgarGirl

I'd go ahead and send him his own at his parents address with her included. When I was 17 I loved getting acknowledged as being my own individual person and not just my parents' daughter.

vmj23

I had a similar situation, a family of 5 and 1 of the children in the family was under 18.  The rest are older (20's)  I sent each their own invite, including the high school student.   I don't know if she was in a relationship or not, but since I was inviting each of her sibling with a guest, I decided to just send her one as well. 

kitty8403

I would allow for separate invite and add her name to his. :-)

aspoonfulofsugar

I agree on the separate invitation.  I am doing the same for my cousin and her boyfriend to her (parents') house.  Even though they are over 17, I would do it anyway because like PPs said, I think it's nice for them to be acknowledged separately.

Edited for wording. 

Grabows14

I was in a relationship with a guy for most of high school. His brother got married, and they sent us an invite to his house with our names on it together. It was a really nice gesture.