OGE has issued guidance on the policy against a federal employee acting as a representative for another person against the government, saying that the exception allowing representation of a parent of child also extends to stepparents and stepchildren.
OGE noted that ethics law generally bars federal employees from acting as an agent or attorney for someone with a claim against the government or in other matters in which the government has a direct interest. That policy however does not apply to an employee’s parent, spouse, child, or any person for whom, or for any estate for which, he is serving as guardian, executor, administrator, trustee, or other personal fiduciary—so long as the employing agency approves and the employee had not been involved personally in the matter in the course of official duties.
The memo said that while the law does not specify who qualifies as a parent or child, its interpretation is that stepparents are covered. So are stepchildren if there is a parent-child relationship that is legally recognized such as through adoption or a guardianship determination, or if the child is a dependent of the employee.
The memo is here: http://www.oge.gov/OGE-Advisories/Legal-Advisories/LA-12-09–Scope-of-the-Exception-for-Representation-of-a-Parent-or-Child-before-the-Government-under-18-U-S-C–§-205(e)