1. If it is "uncle", you can fill in "niece" in the "relationship" column.
2. If it is "niece", fill in "uncle".
Legal basis: Article 31 of the Administrative Procedure Law of the People's Republic of China, the parties and legal representatives may entrust one or two persons as agents ad litem. The following persons may be entrusted as agents ad litem: (1) lawyers and grassroots legal service workers; (2) Close relatives or staff members of the parties concerned; (three) citizens recommended by the community, units and relevant social groups where the parties are located.