I was thinking of squares and rectangles shirt for his brother (who tend to be a working class kind of guy) though possibly more fitted for my huband who tends to be a finer dresser.
Skip the pattern. I recall from a previous thread that your Brother-In-Law is a fellow seafairing man. If so you're in luck! The 1852 Naval uniform stayed in service until 1866 and is an easy draft. It consists of a jumper drafted entirely from rectangles, 13-button fall-front bell-bottom troswers that you can draft from Minister*, a flat hat (two circles and a band) or a straw hat, and a silk kerchief. The summer uniform was made entirely of white duck. The winter uniform was blue wool -guess which shade
Here are the regulations:http://www.history.navy.mil/faqs/faq59-28.htm
Here are some more pictures of tars:http://www.navyandmarine.org/historicalref/usn_uniforms/index.htm
Let me know if there's anything I can provide to help.
*In the Shep reprint edition the basic trowsers include the calculation for the bell-bottom, which is nowhere near as pronounced as the ones seen in the disco era!
**Embroidery was common, often very elaborate, and very much to the whim of the individual.