OK, what exactly are you planing to do? Port a mod to the E3 map? NWO or Kaiser?
Sayd did a dh to E3 map province ID to province ID conversion a few pages back. Find that.
You MAY be able to slot that ?? into Bizon's mmc program, which was used to port hoi2 maps to dh. Possibly ask Bizon about it. I may have already, but I don't remember (honestly, bad memory)...
If you download the E3 map for dh on page one, it is already inside DH for you. I think the DH version may be a little different, but you can simply slot in the newer files if it is.
SO the E3 map will open up.
Say you want to play your new mod as Germany?
Open up the GER files in the mod, WORK ON COPIES, and simply change the province ID's in the events / Ai files one file to the other.
YES when you start, after a while you will say "xxxx this!" BUT then your ingenuity will kick in and you'll think of a better way and easier way to do it.
GREAT if you are already familiar with coding or working with text expressions.