Legal analysis: sign in in person, one person for each account. Of course, whoever wants to do it will sign it, regardless of whether the primary account and the secondary account are the same account.

Legal basis: Article 2 of the Social Insurance Law of People's Republic of China (PRC) The state establishes social insurance systems such as basic old-age insurance, basic medical insurance, industrial injury insurance, unemployment insurance, maternity insurance, etc., to guarantee citizens' right to receive material assistance from the state and society in case of old age, illness, industrial injury, unemployment and maternity.