It sounds easier than what you posted above, but I don’t know if I’m reading your first post right.

"
stored bit0,1,2 = value 4 = display byte- bit3 on, display byte bit0-2,4-7 off
“
Is that the same as saying:
displaybyte.bit3 is set and all other bits are off, so in a different byte, set it’s bits 0,1 & 2 to a binary 4 so the new byte is 00000100 ?