How do I use MacPorts' NTPD over Apple's?

[Dave Horsfall]

I'm trying to diagnose a weird NTP problem here (Sierra 10.12.6) whereby 
although it gloms onto one source, the rest remain in ".STEP".  Given that 
Apple is on the trailing-edge when it comes to third-party software, how 
do I use MacPorts' version of NTPD?  The mysteries of LAUNCHD continue to 
elude me...

Yeah, I could merely kill Apple's and run MacPorts' from the command line, 
but that ain't a permanent solution if it's required.

--
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."