65 Valiant Alt not charging battery, GM HEI no ballast conversion

The object you are calling "ignition relay" is likely the voltage regulator. If you have that wired, and using a 70 or later alternator, yes, you need to ground that second field.

If the harness is original, the wires connecting to the VR should green for the field, and dark blue for the IGN terminal

Once you get it working, a better way overall would be to convert to the 70 and later regulator which will require 1 more wire, and the matching connector pigtail for the VR