There is a misinterpretation on the concept of step children.
I have seen here and there. Where Shifu is referred to as Daniel's stepson, that's incorrect as Shifu was the son of Sha're, and of the host of the Goa'uld Apophis.
Had Sha're not died, that would be correct to refer Shifu as Daniel's stepson.
Although, since she has died, making the marriage dissolved, as Daniel is not the biological or adoptive parent. To which It's inaccurate to refer Shifu as the stepson, instead of Sha're's son.