I've see that problem also.
But maybe, Carlos, could you ask RC to be dependant of the instnce spline?
I've done sometimes RC + Spline to be copied, and everytime i rebuilt, the RC bject move on the first "master" spline, and 'ive to re-assign to the new instances spline... So... could the RC object have a dependance to the new spline? Like a IK rigg copied kept his own hierarchy?