Is the "addr" pin of the chip exposed on your bh1750 module?
If so, you can use this pin to change one module to have one address and the other 3 have the other address. The Arduino sketch would only use the address with one sensor. To read each sensor, use 4 Arduino pins to control the address of each sensor. If you don't have 4 Arduino pins spare, use a pcf8574 chip or similar.
If the addr pin is not useable on your modules, you could use an "i2c bus multiplexer".