Pearl Necklace-ish structures with beads of varying sizes

I’m attempting to create a pearl necklace-ish structure via DupliFrames (duplicating a sphere along a NURBS curve):

So far so good, but as you can see, there is a problem with distribution: instead of evenly spaced distances of origins, the spaces in between the pearls must be the same.

It’s OK if there is no “algorithmic” solution to it, I would also be willing to change the distribution of pearls along the curve by hand, but the question is: how to do it at all?

Thanks for your time.