You need to find the distinguishing property between the 2 different levels and then use a flat list and systems modules with filtered saved views as intermediate steps to achieve this. Taking the above as example-
1. Import all items into a list 2. Create system module with codes and a filter (Code is not blank) 3. Create 2 views: a. Filter = False, for import of parent (P1, P2) b. Filter = True, for import of child (A, B, C.. ) 4. Import data from above
Disclaimer: above is subject to consistent data structure in future.
Change your source data so that the parent and child are separated and easy to distinguish. This is by far the simplest approach from the perspective that Anaplan can convert the data easily into a parent and child relationship. However, it is rarely a simple task from the perspective of the source system.
Create a single list from the data then from this list the parent and child lists. Therefore, it will be a two step process of import the list flat is it is then creating a series of further imports to build the hierarchy. You will need a system to differentiate the child items from the parent. This can be achieved via a formula or manually. Once you are able to do this create two saved views; the parent view and the child list view. You can then wrap the actions up into a process and publish this to a page.