It is very common to have a blended family and there are several ways to list them in an obituary. Just remember, it’s important to include everyone.
For stepparents, write the obituary to say: [Name] was raised by mother [name] and stepfather [name], along with father [name] and stepmother [name].
To write about stepsiblings or half-siblings, write the obituary to say: [Name] is survived by siblings [list all their names] and stepsiblings (or half-siblings) [list names].
If it is a particularly complicated family and you don’t know how to handle all the survivors, you can simply write the obituary like this: [Name] is survived by a host of loving relatives and friends. Don’t worry. It’s not cheating to write it that way! Sometimes it’s better not to get too specific so no one’s feelings are hurt.