I started filling in the form for my husband's 309 application last night, and ran into similar problems on this question as well. It wasn't until I reached the next questionMy partner and I have just momentarily submitted our 820/801 Defacto application Online.
Regarding migrating and non-migrating family members the following two questions are asked:
MIGRATING FAMILY MEMBERS
Q: Are there any family members applying to migrate with the applicant?
A: No
NON-MIGRATING FAMILY MEMBERS
Q: Does the applicant have any family members not included in this application?
A: Yes
I was then asked to supply a list of all non-migrating family members, to which I included the details of 11 non-migrating family members.
Does the applicant have any parents, siblings or children including those that are deceased?
That I realized my error, and went back and changed the answer for the previous question (about non-migrating family members) to No (there is some information provided by clicking the ? but its really not very clear).
My main confusion now, is where we should be listing my husband's minor daughter (she doesn't live with us, and is not migrating), and whether we will need her to have a medical as well.