I know I'm late to this party but to help generally clarify some of the above:
Ezek covers it and his post matches my understanding of KCMO as to OC in county but no OC in the city limits without a CCW and also more generally.
To add some detail as to applicable parts of state statute:
RSMO 571.030. 1. A person commits the crime of unlawful use of weapons if he or she knowingly:
(1) Carries concealed upon or about his or her person a knife, a firearm, a blackjack or any other weapon readily capable of lethal use;
But the exceptions (emphasis mine as to the areas pertinent to the OP):
RSMO 571.030.3
3. Subdivisions (1), (5), (8), and (10) of subsection 1 of this section do not apply when the actor is transporting such weapons in a nonfunctioning state or in an unloaded state when ammunition is not readily accessible or when such weapons are not readily accessible. Subdivision (1) of subsection 1 of this section does not apply to any person nineteen** years of age or older or eighteen years of age or older and a member of the United States Armed Forces, or honorably discharged from the United States Armed Forces, transporting a concealable firearm in the passenger compartment of a motor vehicle, so long as such concealable firearm is otherwise lawfully possessed, nor when the actor is also in possession of an exposed firearm or projectile weapon for the lawful pursuit of game, or is in his or her dwelling unit or upon premises over which the actor has possession, authority or control, or is traveling in a continuous journey peaceably through this state. Subdivision (10) of subsection 1 of this section does not apply if the firearm is otherwise lawfully possessed by a person while traversing school premises for the purposes of transporting a student to or from school, or possessed by an adult for the purposes of facilitation of a school-sanctioned firearm-related event or club event.
IMO (IANAL, etc) you can carry concealed in your yard or other areas around your house/apt of which you have control or authority. So you can CC in your house, on your deck, in your yard, etc. Common areas in say an apt complex are probably no go as you don't have possession, authority or control, BUT since you can carry your gun in your house/apt and you can carry it in your car, there MUST be some way to get it to and from your home and vehicle. While a cop could probably cite you for carry of a loaded firearm across an in-between area over which you do not have primary control, I don't imagine it being prosecuted if you were just going to and from the car or mailbox or something. Now if you were hanging out in complex's parking lot with friends rather than heading straight inside... Meh, probably different story.
The extent of possession, authority or control is interesting. I work with real estate and a conversation came up recently about this as to townhouses and condos. I argued that if common areas are owned by a HOA and controlled by a board of directors, then no defined exemption and back to the "you gotta get it from your house to car somehow" situation. But, if each unit owner owns a proportional share of the common areas then that is possession and an equal authority of the premises with all the other owners for purposes of the statute. Still, with all of this we are presuming a law abiding citizen so why were you having to talk to LEO anyway and there are obviously some very gray areas to this. I'm glad I have a single family home and a CCW.
So parts of this seem kinda dumb in a lot of ways. Basically, in KCMO, St. Louis, Cape Girardeau, etc. there are places outside the walls of your home where you can only CC legally but not OC without a CCW. Kinda the opposite of the recent 9th Circuit ruling in Cali.
Maybe that all helps someone or furthers the discussion. I regret that I wasn't around on the forum when the young lady asked. I hope she had no need for a firearm from when she asked until she was reunited with her husband in SC.