Which looks like the right way to do it. Any new NTP daemon packages which join Debian can have the appropriate relationships declared in their debian/control files. I just checked systemd-timesyncd and chrony, and in d/c they both have:
Which looks like the right way to do it. Any new NTP daemon packages which join Debian can have the appropriate relationships declared in their debian/control files. I just checked systemd-timesyncd and chrony, and in d/c they both have: