Alternate selection srf

[larchbb (bbarchi)]

Hello ! I created this script for a roof structure i want to select the alternate fins for further details .I there any possible way in grasshopper so i can select the alternate fins.I try dipatch and null pattern but iam not getting the exact output.
Roof Script.gh (23.5 KB)

Thanks,

[ftzuk]

Dispatch with the default TRUE/FALSE pattern seems fine.