I dont know why it was suggested that it had to be spawned… it didnt.
it turned out timeline with a spline component was not the way to go.
The correct way to do this, You need a MoveInterpTo component, turn off relative on the control points, then in the constructionscript, loop through a public vector array of relative locations, add those to the actors location and set those to be the “non-relative” points.
This will replicate the platform perfectly. When the platform is Moving down theres a very slight jitter, but this is because of the character,s movement component switching into fall mode, not because of a replication issue.