Oh D., You had my heart palipitating there a second. I thought your brother was a Smith, but I guess he is a Williams. I suggest that he take a yDNA 37 marker test from FTDNA to test for his paternal line of Williams forefathers. He should join the Williams DNA Project https://www.familytreedna.com/groups/williams-dna/about and you may want to transfer your 23andme to FTDNA too: https://www.familytreedna.com/autosomaltransfer
Please use the WikiTree affiliate link for your purchase. This will give WikiTree a small credit for your purchase. WikiTree is free to use, but it is not free to operate, and your DNA test purchase through the link helps with operations costs. http://www.familytreedna.com/cj.aspx?ftdna_ref=600
If you can talk your son into a yDNA test for his Smith line, please let me know.