I agree that a single perp could easily subdue an elderly maid, a little boy with a concussion, and Mrs S. But Mr. S was supposedly trained in art of self defense and was clearly a very fit guy. So it's kind of hard to understand how he was controlled for so long and was allowed to make numerous phone calls to his accountant, to the second maid, to his sister, to JW. Maybe perp or perps were threatening to kill Phillip if Mr. S tried anything (which would have been a lot easier to pull off if there was at least one more perp in addition to DW).