How would you express the fact that a study, report, or investigation provides new information, not included in existing reports? I'm looking for a verb; one that would fit the following sentences.
These additional materials _ the original release, providing a comprehensive picture of the issue. You could add a proof-of-funds letter to your application to _ the limited financial information that they ask for.
They decided to run in-person interviews study to _ two rounds of online polling.
The verb(s) shouldn't suggest that the new information is better — just that it adds to the original one, covering an aspect that wasn't originally covered (hence not "confirm"). The verb(s) shouldn't suggest that something is hotly debated or dubious (hence not "corroborate")
I'm thinking of complement or supplement, but I don't like the ring of either.