create diamond shape

Hi,

I would like to create a diamond shape between four other diamond. The shape with four points from each of the other four diamond. My problem is that I don't know how to select the points from the dimond to create the shapes, i know wich point I need to select but I don't know how. The initial diamond have a light angle I can change so the new diamond must be able to follow. If someone can help me it will be apprciate. My grid is also with an irregular shape and the diamond must be able to follow without crossing other shapes. because the grid rows go from bottom to top in the image «shape». I also join an image of what I wolud like to do. I can do it manually (in rhino) but if I want to change the angle of the diagrid the rest will not be able to follow and I will have to do it all over again.

Thank you