See also AI navigation.
About
AAIController::FindPathForMoveRequest (called from AAIController::MoveTo) calls UNavigationSystemV1::FindPathSync.
Merging
If bStartFromPreviousPath is true on the FAIMoveRequest the result of FindPathForMoveRequest in MoveTo will be merged with the current path of the PathFollowingComponent.
Then it will call AAIController::RequestMove.
AAIController::RequestMove calls UPathFollowingComponent::RequestMove.
Cancel
See UPathFollowingComponent::AbortMove.