If we travel along at a constant speed, without any external forces, it's impossible to tell whether we're whole or broken. However, the state of inertia isn't very exciting or particularly meaningful. It's just safe.
When other forces come into play, things get much more complicated. Instead of stasis we have movement. Mass and acceleration come into play. Things change, and we cant always control them.
Having our entire family back together again is complicated. It's good - definitely good - but also complicated and definitely requires thought.