Hi, I wish it could be possible to split linked cels into halves.
Proposed: When clicking linked cels at specific frame add context menu command “Split linked” to divide linked cels range into two ranges with clicked frame added into second range.
Reason: Simplify adding animation keyframes to existing animations, especially for long animations.
Current workaround: Select second range of cels, apply “Unlink” context menu command, then apply “Link cels” context menu command.
Optimization: No need to select range of cels. No need to apply two commands.
Thanks! 
P.S. When more than one cel is selected it could split into three ranges.