Set the confluent point of some curves as starting point

Hi guys,

I am a newbie here, and this is my first question, so thanks in advance for the support!

The point is that I use both Rhino+GH to export the desired design to SAP2000 in order to make some structural calculations. Due to I work with free form gridshells with bolted knots and the special nature of the design (with openings at the ends), I divide each curve into three symmetrical but unequal subcurves.

The subdivision of each curve pushes me to assign some partial fixity on SAP2000 at the start of the first and third subcurve in order to simulate the semi rigid connection knot. So, it is vital the direction of each curve. 

Unfortunately, each curve or subcurve (frame on sap2000) has its starting on ending point randomly, so I have to flip them manually. Besides, every structure could have more than 250 frames, so it is hard and out-of-the date, to do it manually. See attached file.

Since each knot receives curves with the same X, Y and Z coordinates, I would like to know if there is any way to set this point as starting point of that group.

I hope I've been clear enough.

Thanks in advance,

Paul