Hi Himanshu , In your outcome of level you can set 3 outcome (Approve, Reject and Information required ) . Add you comment in below comment section and In information requested button create a task for requestor . In this case now you will have Task inbox for requestor as well and requestor will receive the task in this inbox ,once requestor resolve the task only after that again the approver will get the task back in his bucket to re-check and take action .
Hi Himanshu Chauhan,
Go through the workflow module to understand https://docs.mendix.com/refguide/workflows/
Once the workflow started we need to set sepearte usertask page for the approvers based on that the workflow task will execute