I wanted to build a "base" unit size of 75k tons, with the following general force structure:
Army (HQ 1M), consisting of 3 Divisions of 225k each, each Division has 3 Brigades of 75k each (two infantry and one armor). Unfortunately it takes almost 6 years to build a 75k Brigade of armor, so I split each brigade in half, i.e. I have four ground unit Formation Templates: Brigade Armor, Brigade Armor (template), Brigade Infantry, and Brigade Infantry (template). A Brigade Armor is half a Brigade Armor (template). Then when a Brigade Armor is done cooking, I set it's template to "Brigade Armor (template)", and when the next one is done (usually around the same time), I set the second one to "Use for Replacements", with the intent that it's elements will be sucked into the Brigade Armor, bringing it up to full size (75k).
I just tried to test this by Instant Building six Brigade Armors and 14 Brigade Infantrys (replacing 20 Brigades I had half-way built). Unfortunately it doesn't seem to be working. None of the Brigade Armors are changing at all, while the Brigade Infantry partially reinforced and then stopped. I really can't make heads or tails of it, hoping I'm just missing something, but it feels like a bug since I'm getting different behavior between the Armor and Infantry variants despite the settings being the same. Any ideas?