(a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to the United States, the consular officer may arrange for an informal examination of the other members of the principal applicant's family in order to determine whether there exists at that time any mental, physical, or other ground of ineligibility on their part to receive a visa.

(b) When family member ineligible. In the event the consular officer finds that any member of such family would be ineligible to receive an immigrant visa, the principal applicant shall be informed and required to acknowledge receipt of this information in writing.

(c) No guarantee of future eligibility. A determination in connection with an informal examination that an alien appears to be eligible for a visa carries no assurance that the alien will be issued an immigrant visa in the future. The principal applicant shall be so informed and required to acknowledge receipt of this information in writing. The question of visa eligibility can be determined definitively only at the time the family member applies for a visa.