I posted a thread just like this a while back, and it looks like you can’t edit curves from blueprint. Something you can do from blueprint is just to set your value to 1 in the curve, and then when you want a customizable value, just multiply the red value by your variable.
What jamen said: have your curve go from 0 - 1 and multiply the value you want it to be at the end. You could make that variable in the construction script too so that you could use the 3D widget feature and set the end point in the level itself.
I never used the 3D widget feature before, so I don’t know how to do it, but thanks for this information, I will read the documentation, it looks very interesting