Ekaton -
I think you're talking about replacing units in a formation that has lost units. If not, then please ignore my post
Replacing Militia units
If the unit is a Militia unit, replacement is automatically done by the zone that provided the units. The higher the zone Militancy level, the faster the replacements will come. Make sure your Militia units are in "Green" Op Logistics, or else they will not get the replacements.
You can increase the speed of militia replacements by raising the zone's Militancy rating.
Replacing Regular units
There are two things you need to do to replace regular units:
1) Build replacement troops.
Click the SHQ your units are assigned to. Click "Repl. Troops" button. Your units will be on the left hand side (Infantry, Machinegun, etc). There will be two numbers, such as (0/1800). This means that your units are requesting 1800 troops to be be sent to them.
Click on the model you want to build to replace the unit with. For example: "Soldier II". Produce the requested troops (1800). If your infantry column goes from (0/1800) to (1800/1800), then you have enough troops to replace your units.
2) Send the replacements to your units
The unit that needs replacement must be close enough to your logistics lines to get the units. Turn on the "Show Op. Log" (or press "6"). If your units are standing in "Green", they are
able to receive 100% of their requests (ammo, food, replacements).
Now, you have to make sure that wherever they're picking up from, has enough LIS points to replace the units. To figure out that number, you take the weight of your units multiplied by the # of replacements you want to send them.
Ex: Infantry Brigade needs 1800 "Soldier 2" replacements. 100x Soldier 2's weigh 5 units.
5 units x 18 = 90 LIS points. Now let's assume Ammo and Food (weigh 1 unit each) consume an additional 20 points. (you can find this out by clicking on the unit card you are supplying, and it'll say it needs how much food and ammo it consumes a turn.) So in total, your units will need to receive access to 110 LIS points.
In our case, our unit will need 90 for replacements + 20 for ammo and food, for a total of 110 LIS points.
If your unit is standing in a "green op zone", has access to 110 LIS points (with no 100% bottlenecks from the SHQ to the unit), and has nothing else using the LIS points (ie: metal from Zone A to Zone B), then your unit will receive the 18 replacements and get fully supplied the next turn.
This doesn't cover other things such as TOE or managing LIS points using overlays or the stats tab. That's another topic [:D]