Turn signals don’t work when headlights are on

Specific to front lighting issue; When a front park/turn 1157 looses chassis ground, park lamp current will use turn circuit seeking a ground. This will light up a turn indicator in inst' panel. I suppose there are a few Darts remaining that dont have bulbs in the turn indicators ( bean counters left them out ( early 69 if my memory serves ) to save a coin until customer complaints poured in ). In that case this tell tale sign of front fixture ground fault doesn't help.
Grounds in general; Once the negative side of a circuit reaches the chassis, in this case core support, it still needs to reach the negative battery terminal. For many, a single factory jumper between firewall and engine then through engine block to neg' battery cable served forward lighting and everything else that is chassis grounded. So that ground symbol of dashes on a diagram could be considered a hint, a questionable path.
At some year model ( I'm not sure when ) the factory added a ground jumper directly from core support to negative battery terminal. Those who don't have this jumper will benefit from its addition.
There are a lot of threads about positive supply and path, improving charging system, head light relays, etc...
The most common mention of improved negative path is adding a jumper wire from instrument panel to dash.
Neg = neglected?