Tu vs. Vous

No matter how long I've been speaking French, there are still moments where I am bamboozled. Tu or vous? It seems like it would be straightforward. But, alas, no. For goodness sake, my mother-in-law uses the vous with me and with Xavier's sister's husband while my father-in-law uses the tu with us. Xavier sent me this hilarious flow-chart he found - a guide for these puzzling pronoun situations. Click on the link to see the full chart.