Blend Animations in AnimComposite/Montage

There’s a feature I miss when it comes to AnimationMontages:

Blending of Anim Sections.

Following Scenario:
I have a Ledge Hanging Animation, I have a ClimbWall Animation, I have a Swimming Animation.
I also have a “ClimbLedge” Animation.

What I want is to use the ClimbLedge Animation for all 3 of them to get onto the Obstacle.
To properly blend them, I need to make 3 additional Animations:
LedgeHanging -> ClimbLedge, ClimbWall -> ClimbLedge, Swimming -> Climb Ledge

Now let’s say I want to change the original ClimbLedge Animation. To make the climb look always the same, I need to redo the transition Animations.

This could be avoided by simply blending animations together in an Anim Montage.

What’s important is, is that the Start-Frame and the End-Frame of the sections need to be customizable.

TLDR; We need something like the Story Tool Blending in MotionBuilder