This is my response to the question about Communist Party member some tome ago for your reference:
Reply - 863211發表於 移民論壇 - 論壇 | 文學城 (wenxuecity.com)
Your father had better write the statement in Chinese about his Chinese Communist Party member and then, you can ask your friend to translate it into English following the USCIS translation requirements. The translator needs to certify that the transation is accurate and then, go to the Notary Public to noatrize the translator's signature. See this link for USCIS translation requirements:
What Are the USCIS Translation Requirements? - Bureau Works
