Ugh, this is so 1995. They actually wore all white on Modern Family and smeared mud all over themselves. Will you all be doing that?
A mix of similar colors/shades, etc. in neutrals looks SO much better and so much less dated. Like, have everyone pick from the colors blue, gray, and white, with brown accessories (belt, shoes), and dress in layers (like a shirt under a cardigan or vest, or a scarf. Then not everyone is matching, but is coordinated so that you see the faces, not the outfits. I disagree that white highlights the faces. It washes people out.
Some nice examples online that could give you brother some ideas.
I recently bought a shirt at Macy's (INC?) that is cut on the bias. It's got a knit back and blouse front, buttons down about half way with pockets and is very flattering. It comes in lots of colors, but I got a white one and a black one.
http://www1.macys.com/shop/product/inc-international-concepts-plus-size-split-neck-cap-sleeve-top?ID=1530211&CategoryID=39720&LinkType=#fn=DEPARTMENT_TYPE%3DTops%26sp%3D1%26spc%3D125%26ruleId%3D%26slotId%3D12