To determine the father-child relationship between a NH and a claimant for purposes
                  of survivor’s benefits, the agency first looks to the intestate succession laws of
                  the state in which the NH was domiciled when he died. 42 U.S.C. § 416(h)(2)(A); 20
                  C.F.R. § 404.355(b); POMS GN 00306.010. If the father-child relationship cannot be established under state intestacy laws,
                  the agency looks to section 216(h)(3) of the Act, which describes a Federal standard
                  for establishing a father-child relationship. See POMS GN 00306.100.
               
               Here, the father-child relationship cannot be established under Colorado’s intestacy
                  laws because CW’s name on the birth certificate establishes a legal finding that CW
                  is the father. Because DA was unmarried at the time of the child’s birth, CW could
                  be entered as the father only if he acknowledged paternity in writing at the time;
                  that acknowledgment is treated as a legal finding of paternity after 60 days. See
                  COLO. REV. STAT. ANN. § 19-4-105(1)(e) (acknowledgment), -(2)(b) (legal finding);
                  § 25-2-112(3)(b) (birth certificate requirements); POMS GN 00306.120DEN. And even
                  if there were not this legal finding of CW as the father, the evidence does not establish
                  any presumptions of paternity for the NH. See generally, COLO. REV. STAT. ANN. § 19-4-105
                  (describing multiple presumptions of paternity). For example, there is no indication
                  that the NH both resided with and held out the child as his own; nor is there any
                  statutory compliant genetic-testing results (results from the mail-order, over-the-counter
                  test kit do not satisfy the statutory requirements). See COLO. REV. STAT. ANN. §§
                  19-4-105(d), -(f) (presumption of paternity when parent resides with and holds out
                  child as his own; presumption of paternity if testing complies with statutory requirements
                  and shows at least a 97% probably of paternity); 13-25-126 (setting forth genetic
                  testing requirements).
               
               The NH, however, could still be deemed the child’s father under 216(h)(3)(C)(i)(I)
                  for having “acknowledged in writing” that the child is his son. For a written acknowledgement
                  to qualify, it must:
               
               • identify the child by name, or otherwise reference the specific child in an identifiable
                  manner, e.g., as the child born to a specific person on a certain date or the child
                  who is the unborn sibling of another named child; and
               
               • clearly acknowledge or identify the child as the NH’s child. POMS GN 00306.105(B).
               
               Here, we think the Facebook messages and posts, collectively, satisfy these requirements.
                  The NH references the child specifically by name; there are photos of the child and
                  the NH that accompany the messages and posts; and the NH is unequivocal in acknowledging
                  the child as his son, including when wishing him a happy birthday on his tenth birthday.
                  The acknowledgment need not be signed, and may be “in any format or on any material.”
                  POMS GN 00306.105(B).
               
               In addition to the written acknowledgment, the evidence must establish a biological
                  relationship between the NH and the child in order to find a parent-child relationship
                  under 216(h)(3). Here, there is reason to doubt the biological relationship because
                  CW is listed as the father on the child’s birth certificate. POMS GN 00306.105(D)-(E). Nonetheless, we think this doubt is overcome by the overall body of evidence.
                  First, DA reasonably explained why CW’s name is on the birth certificate—she was in
                  a relationship with him at the time the child was born, and believed CW was his father—even
                  though she also had a relationship with the NH. DA contacted the NH because of the
                  child’s resemblance to him (both the NH and his mother also commented on the resemblance).
                  Text messages confirm the NH requested a paternity test in December 2018; DA submitted
                  the result of a mail order test dated January 2019. Although the mail order test result
                  includes no names and is not acceptable evidence of a biological relationship per
                  POMS GN 00306.125(B)(1)(b), it does corroborate DA’s statements. In addition, the NH’s mother submitted
                  a statement referencing the paternity test; in a follow-up contact she indicated the
                  NH was very excited to have received the test results and that she observed many similarities
                  between the NH and the child when she and the NH visited the child in the Virgin Islands.
                  Finally, the NH’s memorial service program references the child by name as his “son.”
                  Because DA’s statements regarding the biological relationship are well corroborated,
                  by contemporaneous statements from the NH as well as the NH’s mother, we think there
                  is sufficient evidence to establish the parent-child relationship under 216(h)(3).
                  See POMS GN 00306.125(B)(1)(b) (relationship may be established through statements from relatives or others
                  with knowledge of the relationship that explain the basis for that knowledge).