Thanks for the help. We have three different types of customizations each of which would have different implications on the ETL:
1) Target entity and attribute exist, but need modification (different length, data type, and/or derivation).
Example: change definition of sale amount to include tax.
2) Target entity exists, but we need to add new attribute.
Example: add home_page to employee table.
3) Need to add a new entity to the target database.
Example: add an Event table to the target database.
If these can be done, can you give me an idea of the effort required? Is the ETL designed for easy modification or am I basically writing ETL from scratch to handle these mods?