How to create relationship between objects based on some mapping

I have some object stored as json which have unique key.. And based on these keyes there is a mapping defined in an excel. I need to show some relationship like hierarchy in java class between those json objects based on that mapping.. I don't want to manually create the hierarchy on db for the json based on the ids. But I want to keep the objects separately and based on the mapping I want to create the hierarchy at runtime.. I want to know some best ways or formats that I can keep this mapping . Please guide me .