The highs/lows should already work together. There's a couple different ways to do the 6-hi mod, which keeps the fogs on with the highs as well. I personally would do the second way if my truck had fogs, but its up to you.
check out the second link i posted. pretty easy to do and there's no messing around with the diodes, just pulls a small voltage to close the relay. I wouldn't like having a bigger fuse and the diode and wiring getting hot. just my .02 though
i got it done works perfect i did the relay no diodes i was not a fan of super melting hot wires and jamming things into my fuse box and it only took a short while. well worth it and looks factory. only thing is it doesnt say my fogs are on when my high beams are can you make it?