Hi. I actually use more than one version of a relationship chart to determine familial relationships. I find that sometimes, my mind is not up to the interpretation required by a particular chart, so I will switch to one that is more in keeping with these occasional mental meltdowns.

I am in the habit of using a belt and suspenders approach in determining relationships.

The personal family tree program I use is PAF. PAF comes with a built-in relationship chart. I first use this chart to establish a relationship, then follow up by using one of the following:

About.com
http://genealogy.about.com/library/nrelationshipchart.htm

KINSHIP
http://www.birminghamgenealogy.org/research/kinship/kinship_chart.htm

Lewis Genealogy.com
http://lewisgenealogy.com/relate.html

Stephen P. Morse
http://www.stevemorse.org/relation/calculator.html

Twig, Tree, and Treasure
http://freepages.genealogy.rootsweb.com/~milingenealogy/symbols.html

Spivey