@KARTHICKE16770090 you can use updatecase smart shape. 

https://support.pega.com/question/update-parent-case-properties-when-child-case-properties-change

@KARTHICKE16770090

Create a data transform in the child class and invoke it in the required process 

@KARTHICKE16770090 please accept the solution if you have understood the solution. 

Hi @KARTHICKE16770090

I have removed the solution from @Anoop Krishna reply asking you to mark the solution. 

Could you mark the reply that solved this for you directly?

Thank you,

@KARTHICKE16770090

You don't. Only thing will case rules configuration we can do is Calculate sum of  all child are selective child cases and push it back to Parent Case.

If you need something based on business need, whenever you work on child case if it's from a pega web portal you can use the pyWorkCover page context from clipboard where pyWorkPage will be current the child case you are working on. Then temporarily acquire lock if already not on pyWorkCover i.e., the parent case, and update the page.

If you are working / want to pass the data to parent case where there is no portal in picture something like - through job scheduler / api call etc., in the activity / whichever rule you are processing the current child case, acquire lock on parent case and update. 

Now, coming to flow to update a parent case uses an utility which is again an activity. But using a flow makes the code more manageable and keeps the development clean.

I hope this helps.