Dynamic/flexible spline/sweep in Inventor

I have eight gray "bullets" and some barrels. Bullets and barrels have 3D contact joint. In assembly I try to make new part. Idea is that new part is a spline following highlighted edges of bullets. Pic 1 and 2 show how I want the spline to behave.

BUT when I do the 3D spline it locks all the bullets and I can not move them and have spline following edges of the bullets as in pictures.

What am I missing. Please. Must say I have read helps of adaptive work points all day.