@Curt
I appreciate the advice and take it on board. The thing is now with 127 unit slots it is possible to indulge in a little bit of luxury when it comes to the units. Most of the Infantry types will represent specific Brigades, Divisions or generic units from a Corps or Army. I'm constantly developing the units.bmp, replacing unnecessary units with more vital ones. For example, last night at work I added an Albanian Partisan, (Croatian) Bosniak Militia, altered the appearance of the (Italian) Albanian Militia & Italian Partisan. This was done at the expense of some superfluous Italian, German, Croatian & Russian units. With so many quality unit graphics available it is tempting to try and squeeze them all in (IE having three types of the same unit - one with rifle, one with MP40 and another with MG42) but it is a bit pointless and I'm sacrificing these duplicate slots to include more pertinent units.
It is helpful that a lot of the armour and aircraft of Italy, Germany and Czechoslovakia was used by several civs and I have mostly left of the flags/badges so they can be given to multiple armies. I was keen to include at least one Hungarian built vehicle as they had a really interesting range of home produced vehicles (mostly licence produced variants of Swedish and Czech vehicles) and the generic Lt vz38 can stand in for the Toldi and Turan. I think the Nimrod SPAA is a fascinating vehicle but can't really justify a slot for it. However the Zrinyi is unique and useful enough to warrant an inclusion if I can procure one. I may try and squeeze in the Hetzer somewhere too as this would have been used by Germany & Hungary and is very similar to one of the Romanian tank hunters.
One concept I'm pondering is whether to replace the Allied Civ with Romania. As well as making the map more colourful and interesting it would allow me to give the Soviet army (along with the Bulgarians & Romanians) as well as the British and Balkan Air Force to the Partisans. Trying to replicate the Red Army's campaign in the southern Balkans, Romania/Hungary and the British landings is going to take considerable effort in terms of events & testing. By merging the Allied civ with the Partisans I alleviate this huge burden and also make the final stages of the scenario much more interesting with the player controlling loads of new and varied units in sweeping all arms combat across parts of the map that were previously out of the Partisans reach. The only slight issue I can see is with the city flags which will all show up as the Yugoslav Communist banner, though I see this as a minor anomaly compared with the gameplay benefits. It will also allow me to create some huge German counter attacks in Hungary to add a bit of spice to the final stages of the game.
@Patine
I've had a look. Is it Petite's Barbarossa mod you're referring to? I can see what appears to be a Czech LT vz35 with a cool Romanian/Hungarian/Bulgarian combined flag. I'm using this unit already (minus the flag) as it can be used by these nations as well as be captured by the Partisans.