Relativ Points in SplineIK AnimeBP

I have 10 bones in a line and 4 points in a spline. How can I correctly position the points in the bones? I’ve found that relative values ​​are useless because every point in the location has the value “0,0,0” and was automatically placed along the 10 bones by the system. I also can’t use WorldLocation. What’s the best way to ensure that, for example, ControlPoints2 is exactly on the relative value “50,0,0”? WorldLocation would be even better.