You copy the driver code and data but how do you redirect everything that may have jumped into the old entry point?
You could scan all the interrupt vectors and see if any of them pointed to that driver. Is that the only thing that might transfer to that location? Like, do you have to diddle with the contents of DOS internal tables or something?
I mean, other than the interrupt vector table.
What keeps application code from calling the driver at its old address? The link editor process has already been completed. The JMP addresses are hard-coded.