Only the legal entity (business) that signs the contract is considered the federal contractor with the E-Verify clause and is bound by the E-Verify obligation.
Whether certain subsidiaries and affiliates are a part of the legal contracting entity depends on the specific factual context. Consult your legal counsel if you have additional questions about this topic.
Remember, the Federal Acquisition Regulation (FAR) does not extend to contracts under which all work is exclusively performed outside the United States. The United States territories of American Samoa and the Commonwealth of the Northern Mariana Islands are not considered part of the United States for purposes of the E-Verify federal contractor rule.