SUMMARY
Reply to a SMS from desktop via kdeconnect messaging-application should also mark the SMS, as well as the reply-message itself, on the phone as READ. 

STEPS TO REPRODUCE
1. Receive a SMS on the phone
2. Reply to the SMS on desktop via KDE Connect
3. Check the status of the SMS and the reply-message on the phone

OBSERVED RESULT
The SMS and the reply-message on the phone are still in unread status.

EXPECTED RESULT
The received SMS and the reply-message on the phone should be in READ status as they have actually been read by the receiver.

SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: openSUSE Tumbleweed/KDE Plasma
(available in About System)
KDE Plasma Version: 5.14.3
KDE Frameworks Version: 5.52.0
Qt Version: 5.11.2

ADDITIONAL INFORMATION
Additionally, dismiss the notification entry in the "KDE Connect" plasmoid (popup from clicking on "KDE Connect" icon in the taskbar of KDE Plasma desktop) should also mark the SMS as READ on the phone. I assume it has the same implementation as feature required in the SUMMARY.