sorry if i misunderstand what you are asking (simulation or game ui or what), but here's one take.
in the real battlefield everything by default is isolated and fighting their own battle. the isolated elements do not know much if anything of each other -- they are preoccupied by their own battle.
in a typical WW2 firefight the largest natural unit is probably that of a team: the guys in the team are able to share information and make decisions as a group. this is because they are close enough to usually see one another (at least by popping their head up to observe for a while or by using battle sounds as a cue -- fighting in prepared positions would be different and the natural size of the unit would probably be closer to two men) and hear one another and thus share information (by yelling during pauses in explosions, gunfire and other noise -- here again suppressed or temporarily disabled men may be an exception in that they many not be able to hear or see anything even if it's literally 5 cm in front of their face). the information they share is the type of thinking that there's an enemy at some specific location, of someone about to throw a grenade, of someone reloading their weapon and so forth.
in order for a company to be something other than 20-50 of these kinds of groups of guys fighting their own separated small wars, there needs to be something extra added. adding that something is not automatical or easy, and often there was not much added and the end result was the typical SNAFU or FUBAR.
the first step is the squad leader. he has just about the number of men under his control so that he can see or know each man's general position in most situations. during a firefight he is trying to find out what his men are doing. who's shooting, where's the fire coming from and what is actually happening in very concrete level of things.
once he has somehow managed to get a vague clue of what is happening (both by observing and asking from the guys), he is trying to form an idea what he should do. for example where to position the MG and what sector to give it. where should teams or groups of guys move (on the scale of some individual meters -- for example take cover in a ditch or behind a wall or fire at some treeline).
once he has this idea he is trying to make the guys do what he wants. because everyone is shooting on both sides and there's lots of yelling and all kind of confusion, it usually means he needs to get right next to the men he wants to do something (for example to stop firing so that he can make sense of what is happening, or to get team A to fire at target X that was just spotted by or firing at team . this can be quite hard and it requires a lot of guts, as there are bullets flying, explosions going off, and the poor squad leader doesn't even really know what is actually happening.
in essence the squad leader is trying to combine the otherwise isolated teams into one entity that supports its individual elements and combines its firepower in order to have a maximum effect on the battlefield.
next up in the hierarchy is the infamous platoon leader. this poor fellow controls so many men that he can only see a small portion of them at any given typical moment in a firefight. this means he needs to go out and find out what everyone is doing and what is happening. this is tough stuff because usually he needs to move tens of meters just to get from one squad to another (remember that he needs to have his mouth next to a squad leader's ear, in order to pass a message, and vice versa).
it's also tough stuff because he doesn't have the privilegion of being allowed to just observe what is happening: he needs to tell the squads what they should do. after running from one squad to another a couple of times, after having stabilized the situation a bit, he has to form a theory of what is actually happening on the sector of his platoon. he is trying to estimate what kind of enemy he is facing (about a squad at that treeline, with a MG somewhere near those buildings, possibly another squad further to the left...), what the intentions of the enemy are, what's the status of his squads (2. squad is being suppressed by the MG fire) and what are the possible courses of action his platoon could take.
after this is done he needs to figure a plan. where to put possible reinforcing support arms so that they would have the maximum effect and what to do with each squad. it's a bit like what squad leader does to unite the teams into a bigger whole that supports its elements, but unlike squad leader the platoon leader can not see his whole unit from one location.
then after the has formed a plan he needs to tell each one of the different squads and/or sections what he wants them to do. this he accomplishes again by running around while taking fire from mostly unknown locations. this takes time. if he is slow the situation will change before his planned actions can be executed. if he is too fast or unlucky (or rather with normal luck) he gets wounded or killed at some point of the process.
again the basic idea with platoon leader is to somehow make the different squads fight one and the same battle. to combine their actions. to concentrate their fire. to make the whole platoon utilize well covered path found by A squad, to make the support sections start firing at specific moment as the squads assault across a field, and so forth.
then you have the company commander. he is mostly getting information from platoon leaders, because he can't usually observe the whole company sector from one single position. this is slow process. after he has formed some kind of idea what is happening, based on the reports and partly from his own observations and estimations, he is most likely going to focus on the actions on the sector he considers the most critical. because company sector is some hundereds of meters, there's no way he can just walk or run around from platoon to platoon. radios are cool if they can be used (there's LOS and there's not too much disturbance from terrain and combat actions).
thus he has to choose where he goes. where he goes he adds his experience and the support arms under his command. he makes the platoons work together and according to one plan. i simplify this because this post is already getting awfully long.
the point here is that by default nothing useful happens in the firefight. there's just chaos that gets the men nowhere (except perhaps to the state of even greater chaos). someone must gather information and issue orders. it doesn't happen automatically -- it requires lots of work and time. the higher the number of units (or men) someone needs to control, and the further away they are from one another, the slower and harder the process becomes.
"splitting squads" (it applies as much to platoons and companies), especially when the split elements are not kept connected in space, causes huge increase in the strife to control the firefight. it may cause the whole force to break apart, as the interval between information sharing and order passing becomes far too long to be used to guide actions in meaningful ways (orders always late, contradictory, arrive in wrong order and are nonsensical to the situation).
the fundamental point is that the challenge in the firefight is not to split off elements and send them into their own missions, but to combine the already, by default, separated elements into a one larger unified force that is able to combine and coordinate otherwise dispersed chaotic firepower and action.
if splitting squads (or platoons or companies) achieves the above then it's great. if it has the opposite effect and the decisions are solely based on the godlike knowledge the player has of the firefight and the gamey effects the player can achieve by unrealistic levels of micromanagement and coordination of microscopic elements, then it sucks if it's not properly penalized.