How to give access to someone else's directory via FTP?

Question

linux

Good day!
There are two users user1 and user2. It is necessary to give user2 access to the /home/user1/dir/test/
directory via FTP. The rights to the directory are 775. Accordingly, the owner is user1:user1.
VSFTPD server. Tried to create user user2 like this useradd -d /home/user1/dir/test/ -g user1 user2. When connecting, the FTP server issues cannot change directory /home/user1/dir/test/.
Tell me which way to dig?

Answer 1

sudo mount -o bind /home/user1/dir/test/ /home/user2/some_folder/