This is a continuation of the old FMRS mod, written by @SIT89, and originally continued by @Omegano.
Original thread here: http://forum.kerbalspaceprogram.com/index.php?/topic/72605-110-fl
The new version for KSP 1.4.1 has new dependencies
Click Through Blocker
CKAN has been updated to install the dependencies, if needed.
The Flight Manager for Reusable Stages
FMRS lets you jump back and forth in time.