What is the secondary submit connection on the form that you are talking about? Yes, this is possible without code or qRules - you'll need to use CAML to submit your parent list items and to submit your child list items, but the technique should be the same. There is a pretty good thread here on using CAML for list submits, but I can't seem to find it - you may want to search on CAML and check out some of the other threads.