Laurie, if you go to the court house, just make sure you ask first where the judge's chambers are!
When John and I got married, we had a ceremony planned with about 14 friends and family in Las Vegas at a wedding chapel there. But 6 months before our wedding, John needed to get some dental work done. I couldn't add him to my insurance until we got married and he didn't have any.
We woke up one morning and said OK, let's go get married today. We called the first judge on the list off the internet at the county website and he scheduled us for that afternoon.
We didn't look up the address first, and when we got down there, we were getting married in the county jail. Not the administration building -- in the jail. The judges' chambers happened to be in the jail and he did weddings between the morning felony arraignments and the afternoon misdemeanor arraignments. I couldn't quit laughing through the whole ceremony.
This is so exciting for you! Sounds like you have it well-thought out and have made some good plans for merging families together. The 15 year old will come around -- that's just the age for making everything difficult.
I'm so very happy for you!