Hi there!
It doesnīt sound SO bad ie. past a point of no return....it sounds to me like your spoilt little dog is trying to boss everybody around and tell you where the borders are

I wouldnīt like this from my kids and not from my dog either. The Alpha tipps work really well for me, so have a read again and impliment some of the techniques.
I would suggest that your friends TOTALLY ignore your dog ( for weeks possibly). nobody likes a deserate friend, neither does your dog, so then your dog can come begging when he realises that people are not `begging`to be his friend.
Staying in a place when the door goes is a slow process, but I made it clear to my friends that they may need to wait outside the door a moment longer whilst I deal with the dog first.
We started first with her on the line held by somebody else, and I gave the command to stay, then opened the door, told the person to entirely ignore the dog ( very hard for people to do, but insist!) and welcomed them in.
Now, when the door rings she runs to her place and jumps on so she is in the best possition for viewing the new arrival, and she will stay there till I say. The hardest bit was interrupting my guest mid sentence to tell the dog to return to the place, but I would say čxcuse me,.....`same as I do when the kids are up to something.I do not put being polite to my guests before dog training!
Occassionally the dog will be asked to come to the door with me, but she will sit ( previously on line) and will stay sitting the entire time. Again, I have no problem interrupting the visitor to do this. I`m sure in the long run they will appreciate this

With some regular visitors, the dog is so relaxed she doesnīt even open her eyes to check who it is....I am very proud
The most important thing is to commit to clear rules in your head ie. she will NOT come to the door, she will never greet a guest first, and she will Not leave her place until asked to do so ( a good 15 minutes after arrival is good)
When you stick by these rules ( or other rules that you decide) then it makes it easier to interrupt your guest to enforce this.
Another trick. Over our dogs place for many months was a sign that said in HUGE letters...IGNORE ME PLEASE! sounds crazy but really helped for forgetful friends. ( and of course family!)
Our dog has a clear place that the children and visitors are not alowed to visit. When she is wanting company she comes to the kids, not vice versa.
Give your dog time to be a bit of an outcast, and then watch while your dog trys to sweet talk you all back again !
Your teenage visitors should be able to do the whole `cool-Iīm not looking at you`thing quite well I expect

really lifting the eyes and looking cooly away. Later they could try to give some basic commands for treats.
I think itīs better that you accept that for now you do not have a cuddle bear dog, and donīt be dissappointed. That warmth will come again when your dog feels more relaxed and less pressured to have to `hug`any old person who comes in the house. Iīm sure it would be nice for you to see the dog `laugh`more, but itīs a bit like tickling for us....too much is not so nice!
Find what gets your dog laughing....
hope some of this helps...
take care,
Annie