It can be cumbersome to write master/detail features using FME as you have to pay close attention to the order you write the features if there are foreign key constraints in the database.
I propose giving the FeatureWriter a Group By option, where all the features in the same group (across all input ports) are written to the database inside a single transaction, when the output format allows it. It should also have the option "Input is ordered by group" to prevent the FeatureWriter from being blocking, whenever possible.
This would solve the issue about writing master/detail features in a simple and intuitive way.
