H1B, H4 Visa

We have an f4 visa type, and one member in the family ( my son 19 years old) was given the ds-5535 form to submit (which he did), after the interview.
The CC told him not to worry, because he told her that his university will start this fall, but she assured him that he can defer his entrance to the university until spring.
We were told that they can go on issuing us the visa for my wife (main applicant), me and my daughter, but asked us if we want to think it over first, since my son was not issued yet.
we decided to go on with the visa and that my son can follow us later.
one hour later, we were called and told that my wife needs to fill the ds-5535 too and since she is the main applicant, we were on hold too.
18 days have passed and on the CEAS status only my son is under Administrative Process and we have "READY" status showing.
It was updated once since the interview and it changed from 12 september to 18 september and still shows"READY", but my son was not updated and still shows 12 september AP.
the forms for DS-5535 we filled on the same day and emailed for both my wife and son.

[P.S My wife got a visit visa last year for 5 years and was asked to fill the ds-5535, and got an answer in 10 days, but when the counselor was going to stamp a new visa she told her that she will need to cancel the old one, which she did]
Can any one explain what we are going through, thanks