We know the limits of the Dwc star schema to represent a relationnal database.

For example in the case of 1-n cardinality :  specimen --- event/record --- location.
If i understand the concept, I need to use the Darwin Core Occurrence extension, denormalize my relational model in a big raw model and transform / re-normalize this model to match with my DB model.

In order to reduce cost, dev and optimize sql statement, it will be grandly appreciate to add custom extension. In this case, i can to be very close of my relational database model and avoid multiple step of dev.