It takes about 7 working days to add relatives for single authentication, and it usually takes about 15 working days for dual authentication. According to the query of relevant public information, you need to obtain a notarization of kinship before applying for kinship certification. You need to set aside time for notarization (7-15 days) to avoid delaying the processing time. The required cost is generally around 200 yuan in China and around 400 yuan in foreign countries. If you choose to expedite the process, the cost will also increase, which is subject to the actual situation.