I'm in a new (to me house) that I suspect all of the wiring was redone 10-15 years ago. We're installing overhead lighting, so I'm trying to change the switched outlet to be constant power. I've done this elsewhere, but...the wiring on this o e is different and I can't seem to find a matching diagram to confirm that my plan on this is right.

To me the odd thing is that there are THREE romex wires coming into the box (two three-wire and one four-wire). To my knowledge (and testing), there are no other receptacles controlled by the switch. Obviously the four-wire romex come from the switch, but I don't know where the the other go/come.from except that there are two other outlets on the same fuse (both would be "adjacent" receptacles on each side). It's also worth noting that the same fuse does have two other switches on it that control and outdoor light and some hallway lights).

So...my assumption is that I can simply remove the four-wire from the receptacles and rewire a new gfci outlet in parallel. See diagrams for existing setup and what I am planning on doing.

Is plan good? Is there anything I should be worried about?