Obviously being from East Africa is not the best way to become an Olympian. There’s too much competition. You need to pick a country without much running success, but where there will be access to the necesssry things. I think Italy is a good candidate. Not many Italian distance runners, yet it is the home country of Canova, plus opportunities for high altitude training.
If they are born in Italy they can be an Italian citizen. Additionally, it would be very easy for them to be out playing soccer constantly, on a club or just in pickup games.
In addition to soccer do as much very easy running as they want and encourage them to play tag etc.
Have a very well balanced diet, take a vitamin or two, etc.
Eventually you will begin training them for real and should begin by building up the easy volume and getting them to handle a steady number of higher end, but totally aerobic runs. Enter them in races where they will have fun and acquire a joy for racing.
At some point you should either send them to the states to run in the NCAA- pick the school for the coach obviously (perhaps Wetmore would be good)- or have them train in a more serious club environment.