I want to monitor the change of parent address while sending the packet .
But in this code you are not sending the packets, you just lining them up to be sent much later. After encryption, route discovery, retries, etc.
I think am calling appDataConf after sending each packet.is .
Stack must call it. You calling it does absolutely noting.
You are missing the point of cooperative multitasking. This task just lets other.
Look at the code and see that NWK_DataReq() does not talk to the radio in any way.
or else how can I send data with updated parent address value in this flow .
You send one and exit while waiting for appDataConf() to be called. Then you fill the next request right in appDataConf() or use it to schedule a task (change of application state) that actually sends a message.
You will have to work with stack machines, just like sample applications do.