Help needed Wedding invites with no names

Hi, WE have bought our wedding invites from wedding paper divas in America. They were the cheapest option. However it seems to be the style to not right the names on the invite, I was just wondering how to address the envelopes. WE are getting married away so we are only inviting aunts and uncles due to my other halfs large family. but we only want the aunts and uncles to come and not all their children. However, there are couple of his relatives who have young children so we appreciate they will need to be invited as they obviously wouldnt travel without them. Do we right the kids names on the envelope? I am worried if we dont right the childrens names on the envelope the other relatives will assume their children are invited and it will end up too many. Also how do you put a plus one on an envelope

I'd put the children's names on the envelope alright. Not sure about the plus one thing though. Anywhere on the invite you could write it in?

Is there definitly no where on the invite that you could pop in the names? Writing everyones names on the envelope would be fine for the people who you actually want to bring their kids, but I think problems could arise with the people who you don't want to bring their kids. They might assume with no names specified on the invite that everyone in the house is invited. The envelope is going to end up in the bin with the invite being stuck up on the fridge.

Could you put the names on the top left hand corner? That's what was suggested to me in a print shop.