A long distance senior move is really two projects: deciding what makes the trip, then moving it. Sequencing them in that order is most of the battle.
The short version: sort first, survey second, book third. The estimate is built from what's actually travelling — so the family decisions about what stays, goes to relatives, or gets donated need to happen before the surveyor walks through. Get that order right and a senior move becomes an ordinary move with extra care; get it wrong and the price changes on moving day.