The Berry Amendment applies only when purchasing the 11 items listed at DFARS 225.7002-1. There are a number of exemptions so be certain to review DFARS 225.7002-2 to determine if any apply to your acquisition situation.  As to your basic question, I see no reason not to share market research with the prime vendor if doing so will help comply with the law (Berry Amendment). You may want to put in writing that identifying the domestic source in no ways constitutes endorsement of that source. This way, the prime vendor can't misinterpret the information as being an endorsement. If other vendors were involved in meeting the Government’s requirement it would be necessary to share the information with all in order to maintain a level playing field.  Finally, since you mention the "liability" issue, I recommend you consult with your organization's legal counsel for a more authoritative response.