Octagon Grid + Squares /tree of items from different branches

Hi everyone,

I have an octagons grid and I would like to fill with squares the space left between each octagon.

As you can see in the picture I should create a new tree as follows..
I.E. Branch {0;0}:
From octagon {0;0} take item (0) and (1);
Move to octagon {1;1}, take item (4) and (5);
and put the in the branch {0;0}

in the definition in attachment I obtained a good result but since I am a newbie I'd like to know if this is a smart way to go of if there are shortest ways.. maybe with Path Mapper?

Thanks