Hi Michael, thanks for answering. I should have remembered Isect, a little rusty after sometime away from drawing. Feel like I should be able to create an arc between points (created by Isect) and the surface of sphere (either inside or outside), but unable perhaps because points aren't really on surface. This could be because of some inconsistency in my drawing. Curious if I should be able to create an arc on surface ? So instead I created a closed curve between said points and "project"ed onto sphere surface after changing cplane to the origin.

Thanks for patience, Sven