xtrabackup to create multipule slave channel for mysql 5.7


Could you please confirm how to use xtrabackup to make multiplue slaves against 5.7?

For example, I have databases D1 and D2 in mysql A; And D3 and D4 in mysql B.

I want to create two replication process in the mysql C. One is to get data from D1 in A ; the other is to get data from D3 in B.

For now, I have to use mysqldump. If the tables are large, the performance is a big problem.