I think you are correct and have identified the need to tap into things logically as far upstream as you can, i.e. emulate the key or the button, rather than directly triggering the relays that power the solenoids. This way there won't be a problem with firing the locks with open or slightly ajar doors, and the car should know what state the locks are in.
On the other thread the plan is to plug in the keyless receiver unit from a higher spec car, and pair it with an old Jazz fob. It sits to the right of the under-dash fuse box against the side of the car; you might just be able to see a spare four-pin connector there, but would need to remove the panel for full access. It's four wires are 12v, acc-12v, gnd & output. I don't know what the output is, I might try it on the bench to see if it's just a 12v/ground/open, but it might be a data signal, will know more middle of next week. If it's simple then bingo - that may also be an ideal trigger wire and probably a good space & power supply for the Hawk.
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TG