Cynthia Jacquier

Hello. My daughter, son in law and I are traveling to Istanbul in June to meet with his mother, who is a citizen of Tunisia. She has a valid passport and a return ticket, but does not have a bank account or credit card. My daughter and I are US citizens/ passport holders and we will be hosting her visit. Could you please tell me how we can best show proof that we will be financially responsible for her? Will a letter showing proof of accommodation suffice, or do we need something more? Thank you, in advance, for your time and consideration of this matter! Sincerely,