Actually, it should be trivially easy. I specifically made sure what you are requesting is possible to do. For any intrepid player that wanted to continue to play with their Grand Campaign army in new adventures, either modded or official. This is why Grand Campaign 1945 E and W both save your CORE at the end instead of just END, even though there is no official 1946 DLC. Just for people like you.
Yea, I tested this and verified 100% works if done properly. Easily do-able in just a few minutes, if not seconds.
I'll walk you through it.
What you need: Microsoft excel. This is important to preserve the correct file formatting. Simple text editing of the entry cells with ruin the whole file without excel to organize it.
As with all modding, make copies of files you intend to edit just in case.
1. Open campaign.pzdat in microsoft excel. This file is found in the game's root directory. For example D:\Games\Panzer Corps\Data or my steam location is D:\Games\Steam\steamapps\common\Panzer Corps\Data
2. Open campaign.pzdat in microsoft excel. However instead of the same campaign.pzdat file as step 1, now you need a Grand Campaign DLC campaign pzdat. Let's steal from 1940. Steam\steamapps\common\Panzer Corps\DLC\GC40\Data
3. Copy cells H, I, and J of
horizontal ROW 7 from campaign file you opened as part of step 2, and paste them into the campaign file from step 1, overwriting the same H, I, and J cells
which in this file is horizontal ROW 8.
Save changes, launch game. Now when I start Poland from the base game, the game asks me if I want to important a DLC 1940 force into the base game. Viola. Done in three steps, all you did was open 2 files and copy paste from one into the other and save changes.
Finishing up:
A. Now of course you wanted to take your 1945 CORE, so you want the game to ask you for a 1945 CORE not a 1940 CORE. You need to change the GUID, that's the long string of random letters and numbers, from the 1939 code to the 1945 code.
You need to change Column I from {C6FE45B9-F408-45af-9709-1064FDC83694} to {B450AE10-3D6A-4e78-B2FD-C78E03DC1E70} That's the 1939 code on the left(who imports into 1940) and the new code is the 1945 East code.
B. As niki did correctly point out though, if you want to deploy your army into the first scenario, you have to edit the scenario to place deployment hexes into it. Or if you don't want to take that step, you can just play the 1st scenario normally, buy some temporary units and quickly smash Poland, and then all future scenarios that have proper deployment hexes in them will allow you to deploy imported 1945 units without difficulty.
When you open in excel, the text should format extremely nicely within the cell structure. For example, horizontal row 8 should read:
Poland 7 IDS_CAMPAIGN_DESCRIPTION2 0 0 964 IDS_CAMPAIGN_NAME2
And when I ask you to read me the value of cell 8 F, you should clearly be able to tell me it says "964"
If that doesn't work, or is unclear, or you don't have access to microsoft excel, you will be in trouble. But if you survive this step, it's clear skies ahead.
You start with
Poland 7 IDS_CAMPAIGN_DESCRIPTION2 0 0 964 IDS_CAMPAIGN_NAME2
Change it to
Poland 7 IDS_CAMPAIGN_DESCRIPTION2 0 0 964 IDS_CAMPAIGN_NAME2 Grand Campaign {C6FE45B9-F408-45af-9709-1064FDC83694} END_SAVE_CORE
and finally end with
Poland 7 IDS_CAMPAIGN_DESCRIPTION2 0 0 964 IDS_CAMPAIGN_NAME2 Grand Campaign {B450AE10-3D6A-4e78-B2FD-C78E03DC1E70} END_SAVE_CORE
Using this method, you can import these saved CORES to any campaign you want. Good luck and have fun!
