The first thing you’ll do is examine the two three way switches you are going to remove. That black, red and yellow wire will be connected to screw terminals on the switch - two of these will be the same color (like brass) and one will be another color (like black). If that’s the case then the two wires on the same color screw are classically the “travelers” I was talking about for a 3 way circuit. The third wire will be the line on one 3 way switch and the load on the other 3 way switch. If you review the basics of how a 3 way switch works you’ll understand this better but all the switch is doing is transferring the line voltage to one or the other traveler wires through to the other switch which either places it in continuity with the load or not depending onthe other 3 way switch position.
You’ll then remove both 3 way switches and when you do that you will line voltage on only ONE of the wires in one of those 3 way boxes. All the other wires will NOT have line voltage.
You will then use one of the two travelers to pass the load from the 3 way switch box into the other box (because the master GE switch needs line and load and traveler in the same box as well as neutral you said you’d supply).
You will then install the master GE switch into that box and once you do that and turn the power back on the light will actually work from that one switch.
Next you’ll install the two “addon” switches. All those require is line voltage, neutral and connection to the “traveler” coming from the master switch. The same traveler can be used for both addon switches.
The only issue you may run into is that 4 way switch box. If it only has those 4 wires in it then you’ll need to run line voltage and neutral to it from anywhere else.
As always it is best to perform all your wiring with the breaker off for that circuit (after you’ve investigate where the line and load wires are). I also always wire those ge switches with the air gap pulled out (that’s not how they come out of the box). This protects the switch if you happen to connect it to voltage before being fully hooked up. Those switches can be internally damaged if that occurs.