Reversal was required where DCFS did not exercise due diligence in noticing father by failing to perform a search based on the unique information provided. During the dependency proceedings, father’s whereabouts were unknown. DCFS filed due diligence reports that it had served four local addresses and placed notice in a Los Angeles publication. At the September 2017 section 366.26 hearing, father’s whereabouts were still unknown to the court. However, older half-sister Blanca appeared and DCFS was ordered to assess her for placement of the minors. At a visit with Blanca, the minors talked to father by cell phone. Blanca also told DCFS that she had contact with father via Facebook. DCFS received father’s phone number in Mexico. DCFS was unable to reach father at the number, and served mailing addresses in California only. DCFS never asked Blanca about the Facebook profile or did research regarding father’s whereabouts in Mexico. In June 2018, father’s whereabouts became known. Father communicated to DCFS that he was interested in custody of the minors. The court ordered counsel to reach out to father and determine if he wanted counsel appointed. Father expressed his interest in being represented. In July 2018, father filed a section 388 petition asking the court to vacate the jurisdiction and dispositional orders as they pertained to him, for lack of notice. The court denied the petition, stating that it was unreasonable to ask the Department to attempt to locate father in Mexico. On appeal, father contended that the court violated his right to notice because DCFS could have found him through Facebook or by questioning the mother. He further argued that all orders pertaining to him should be reversed for failure to comply with the Hague Service Convention in order to acquire personal jurisdiction over him. The appellate court agreed, finding that DCFS’s efforts did not constitute reasonable due diligence. DCFS had searched standard avenues available to help locate a missing parent, but failed to search the specific ones mostly likely under the unique facts known to them to yield appellant’s address. It failed to follow the simple step of calling directory assistance or follow through on father’s Facebook account. Both of father’s older children were cooperative and available, but DCFS did not take advantage of their Facebook access to father to provide notice which was reasonably calculated to apprise him of the proceedings. DCFS searched United States databases while well aware that father had been deported to Mexico. It was not unreasonable to ask DCFS to locate father in Mexico because DCFS had leads from cooperative family members. Because the Hague Service Convention applies, and its requirements were not met, automatic reversal is required.