Thank you for you input ... indeed everything went well in the interview and they haven’t asked for any additional documents for me of for my children!I am not sure why the delay only for your children; is your application non-routine? I.e did they request additional documents after you submitted the application?
Regarding the oath, I think it mainly depends on what date you applied; i.e since your application timelines have crossed 12 months, whenever they get the next set dates for your location, you might be one of the first to get invited as compared to someone who applied a few months after you
I hope who passed in the same experience could give us a feedback about this issue