First of all, in todays "blended families", it is not necessary to point out "less biological" relatives with "Half, Step or in-law" before or after their association to the immediate (or current) family. All this does is confuse children and belittle the person in question. Just consider that He is your brother, his son is your nephew, and if your parents are married, they are his Grandparents. Leave the hyphens to inquisitive strangers and just be family.
參考: Never had biological kids, but adopted 5 kids and have 2 Grand Daughters by 2 step kids. "Blended"