As for following frequencies, it will only do that automatically on P25 systems and the rare DFA (direct frequency assignment) systems.
Otherwise, for DMR and NXDN you are going to have to set up entries in your DSDPlus.networks, DSDPlus.Sites and DSDPlus.frequencies files for any DMR or NXDN or IDAS trunked system before it will follow voice.
Copy the info to the appropriate file (the files already exist):
DSDPLus.Networks
---------------------
; SaiaNet
CON+,171,"SaiaNet"
DSDPlus.Sites
---------------
;SaiaNet
CON+,171,23,"UB Cooke Hall"
DSDPlus.Frequencies
-----------------------
; SaiaNet
CON+,171,23,5,462.100,0.0,0
CON+,171,23,13,461.525,0.0,0
CON+,171,23,15,461.600,0.0,0
CON+,171,23,21,461.85,0.0,0
and I can't remember if you need L157 below or just 157 below
DSDPLus.Networks
---------------------
; FM Communications
NEXEDGE96,157,"FM Communications"
DSDPlus.Sites
---------------
; FM Communications
NEXEDGE96,157,2,"Tonawanda"
DSDPlus.Frequencies
-----------------------
; FM Communications
NEXEDGE96,157,2,4,424.700,0.0,0
NEXEDGE96,157,2,5,451.9375,0.0,0
NEXEDGE96,157,2,6,461.95,0.0,0
NEXEDGE96,157,2,7,463.725,0.0,0
NEXEDGE96,157,2,12,452.800,0.0,0
NEXEDGE96,157,2,13,463.45,0.0,0
NEXEDGE96,157,2,14,464.45,0.0,0