Need help-- Auto-tabulating data with Microsoft Visual Basic in Excel

Hi,

I'm currently trying to write a code/script using Visual Basic, however not sure if it is possible.


Scenerio:
For instant, a building is controlled by the main power source..if it goes down/faulty, all the facilites in the building will be affected and without power.
If any one of the sub-power source goes down (eg B, C or D), only the associate facilites controlled by that sub-power source will be affected.
eg if B goes down, only E will be affected.
if D goes down, only F will be affected, because G connects to H as well and H is ok. (G connects to D and H sub-power source)

A = main power source
B, C, D, E = sub-power source
F, G, H, J= facilities

A
/ / \ \
B C D E
| | / \ /
F G H J


I may just need to enter the function in one of the cell in EXCEL, ( by referring the value in another cell and it will extract the info from a file) and it will tabulate the facilities which (of the above) are being affected.

For eg. A goes down, and it will show B thru' J go down
H goes down, and it will show L goes down (because G connects to D as well,therefore will not be affected)


Appreciate if anyone could be able to give me some suggestions/solutions. Many Thks.