Ok, I get very into planning my WDW vacation. I look at my time at WDW as MY time away from the world. My honey and I really feel so much closer to one another there, mostly because we both relax and can spend time together. I have been working on the plans for our December vacation for almost a year. I have romantic things planned as well as just some wonderful opportunities to kick back and take in pixie dust. Needless to say, my plans are for us alone. We have saved for the last 15 months like crazy to make this happen.
My honey's family lives in FL. Her mother is the first love of her life and they are extremely close. Her mom wanted to join us on this trip. To put it plainly, I wigged out. lol She has many health issues and she is very tight with money. Needless to say, having her along causes me MAJOR STRESS. So, to compromise, I was forced to blow the surprise that I had planned for her. Yes, I was trying to be nice to the mother outlaw....it does happen. lol Anway, we told her about the Afternoon Tea at the Grand Floridian that we were going to take her to before we actually arrive at WDW for our vacation. She was totally cool with that. Thank God!
In your situation, I can see where the whole family is helping out with the money thing would make it harder to stand your ground. I totally understand how disruptive and almost heartbreaking it can be to have all your hard work and planning fly out the window. But, in this case, you have a couple of windows.
#1. Go see your uncle and aunt before you actually go on vacation. Show them your itinerary. Let them meet your DBF and let them know that your trip is of a romantic, not family reunion, nature. I think you might see that they will understand and not actually want to blow your day.
#2. Bite the bullet and rework your itinerary to work them in somewhere some day. I know, this one sucks pond water.
#3. See if they actually even want to see you to begin with. Sometimes older folks in poor health don't really want to be obligated to deal with a trip to WDW either. You might be surprised.
I wish you much luck. Mickey