You will have to register 3 different companies but all as a subsidiary of the main company.
Its expected that all the minimum share capital most be meet by all the companies .
Minimum share capital
1) BDC - 35 Million
2) Forex - 1 million
3) Microfinance - (Unit - 20 Million)
( States - 100 Million ) ( National - 2 Billion )
Also remember that you will have to meet the CBN Regulations for all the companies.