@yt110154 could we go back to the business outcome? What is the scenario trying to be achieved.
It sounds like the parent and child are both looking at a list of items? Let’s say addresses, when I update my billing address in the child, we want to make sure that the parent see’s the new billing address?
In this case, a saveable datapage would work OR a list view on the “address” data object with CRUD enabled. See Configuring Actions for data objects or Managing external system of record through REST with CRUD actions in Pega Constellation.
An “on bulk” change of data objects, where all are editable is not possible with saveable datapages, even in the UI this is not possible (until '26). I would suggest using embedded data in child and/or parent, then individually saving those back to the data object. You’d have to take care to show the data reference when in read only and copy the data reference to embedded when you want to edit.