S3423DWC & U2722DE KVM and MST

How can I get KVM working with 2 computers and daisy chain the 2 monitors to work together so I can swap dual monitors at the same time? I've turn on MST on U2722DE, but there's no MST option on S3423DWC. I tried to connect computer on U2722DE, use DP out from U2722DE to USB-C on S3423DWC but computer doesn't seems to recognize S3423DWC. 

Any ideas or suggestions? Thanks.