My DH and I were both married and divorced before we met each other and I had a 1 year old DD from my previous relationship. DH comes from the US and I'm here, we decided that when we got married we were going to have no one there at all. We decided that if we had it here or there one set of family or friends would miss out. Also having felt that both our first weddings were about everything but the actual 2 people getting married we didn't want that this time.
In the end we got married in the US, but didn't tell his family or friends so they couldn't be there. My family and friends knew, and my mum had DD so we could have a honeymoon too. It was beautiful, touching and about our love. We had a video made and showed everyone after. His family were disappointed to have missed it but understood that with a tranatlantic relationship there was never going to be a way for everyone to be there unless we were mega rich, which we're not!
I know your DD is not in a transatlantic relationship, and I totally understand that you are upset. Would you be willing to perhaps compromise and arrange a blessing for you all to attend, whilst letting her have the wedding the way she wants?
My first DH didn't talk to his family and they weren't there for my first wedding, when he eventually made up with them, we never heard the end of it, why my family were there and they weren't, so I can understand why your DD wants to avoid this.
Its a tough call, and I don't think that you are being unreasonable, unless it gets to the stage where you DD doesn't get married at all, as she is threatening, in which case I think you are going to have to sit down a work out a way to keep you both happy, even if it means you don't get the wedding YOU want.
I hope I haven't offended. I just think it could lead to a bigger problem in your relationship with your DD if some solution is not reached where you both feel listened to.