# Keying relative value when mixing animations with NLA editor like in Maya

I'm working in NLA editor and I have two tracks enabled with additive blending. One track contains an animation with Y location of an object keyed. The Y location fcurve has value of 10.0 on frame 1. The other one is empty. Both tracks are active. I select action tweaking on the second action. Select the first frame on the timeline. Edit the value for Y location to 15.0. When I then key it I would like it to key the value of 15.0-10.0=5.0, aka the relative value to the first action. Instead it keys 15.0. I could of course just key the value of 5.0 and it would work as needed, but when mixing more complex animations you want to see how it looks with the result of all other animations before you key it. With all this I want to replicate the animation layers in Maya for additive animation.

I tested this in Blender 2.8 and it does what I want by default. But in 2.79 it keys the absolute value. Are there any settings I can change to change this behaviour? Unfortunately completely moving to 2.8 is not an option for now.