4 prong relay

Excellent, you showed several ways to do this. Most likely the negative control will be used but many systems put out both on the doorlock outputs so either may work,

Although there would be no point to applying power to both controls, and the system itself , and any switches used if functioning properly would not do this, it actually wouldn't do any harm. It would simply send 12+ to both legs of the actuator and no current would flow, similar but the opposite of what it is doing in its "at rest" state, each leg is recieving 12- with no harm. (or vice-versa), it just wouldn't operate the actuator.

In the 3rd diagram (negative control motor) although this would work,  IMO I prefer to not ever have the legs rest at 12v positive since these run from the relays, through the door jams, into the doors. Too many risks of a short to ground. (blown fuses or worse if installed improperly) In addition, any manual switch(es) installed to operate the locks as well, can be negative, hence less running of "live" 12v +power throughout the vehicle.  I would prefer to use diagram 1. As long as one side of the relay coils are on 12+ constant, a negative on the other will activate the relay.