I celebrated my 80th birthday last summer. I have five adult children and eight g.children, (age range then 7 yrs to 20yrs). The children all live, fortunately, in England, but scattered about. All I wanted was some way of having them altogether.
My two eldest daughters made an arrangement for lunch at a gorgeous pub, not close to any of us - so all had to travel.. Although this was arranged outside, - just in case the weather was bad, it also had a large shed like thing with heater attached to this patio.
Actually, we got one of the hottest days of the year. I had no idea all this had been arranged. Was just collected by local daughter and family to have a lunch with them. Was surprised are how far we travelled, but brilliant surprise when I got there and all of them were assembled. Even my son and his wife who had visited me that weekend, and to whom I had said a farewell to the previous evening, thinking they were going to drive back to their home up north in the morning. Another of my daughters' made a beautiful cake which on one layer had (eatable) pictures of my children and on the lower one eatable pictures of my g.children.
My DiL made a wonderful photo album from the pictures taken there giving me a great keepsake of a super day.