You cannot have multiple inverters connected in anyway, they will be out of phase with each other and cause a short.
I grounded (green wire) the recepticles to the bus, which really doesn't do any good unless you also ground the bus in some way.
Then I ran run the black wire (hot wire) and the white wire (neutral or common wire) to the switches and outlets that a want that inverter to power. You must keep each of these circuits seperate between inverters. You will need to decide what you want each inverter to power and only hook up that one inverter.
Not sure what you are trying to do but I should point out that if you want to use multiple source (although you can only use one at a time as I pointed out) a transfer switch can be put inline to move your circuits between sources.
Lets take for example you have a circuit that runs all of your kitchen area appliances and it is plugged into a transfer switch. One one side your 1000W inverter is plugged into it. On the other side you have plugged in one of your 750W inverters.
Lets say you want to use this single inverter to power everything and only turn on the other two smaller inverters when you need the extra power. So you can have this 1000W inverter powering everything and if you know you are going to need some extra power when you use your microwave you can turn on that other 750W inverter. When you do this the tranfer switch will see that you are now supplying power on the side and it tranfer your kitchen circuit over to running off the 750W inverter, leaving the 1000W inverter to power everything else in the bus except this circuit. Then when you turn the 750W inverter back off it automatically tranfers over to the 1000W inverter again.
This is how most RVs switch between generator, inverter, and shore power. Tranfer switches are very handy and if you use them in the right places they can be very power tool. Also you can buy inverters with built in transfer switches, the one I have in my bus is one of these.
Here are some examples of just tranfer switches: