@Ash, kindly please be informed that the way you wish to flow the survey questions is not possible. The only option/approach that is possible is you first finish the repeat group, then once you move forward to the next nested group, you will need to fill up all the questions from that nested group and likewise proceed forward. I mean there is no option of moving back and forth during the survey.
This post discussed previously should show you how the repeat groups are handled by the system:
