Blackwell, also based in Northampton, said he discovered the group on the internet in 2017.
The musicians had “got together at this sort of secret school and formed an all-female orchestra”, he explained.
He told BBC Radio Northampton that some of the members had “faced backlash from their family, some have been rejected by their families, there has been disputes, and there have been death threats”.
The musician and filmmaker said the orchestra has played around the world but had not been able to perform in their home country.
After making contact with the orchestra, they invited him to Afghanistan to meet the musicians.
He travelled later in 2017 and went to the school where the orchestra was based which was “walled off and had armed guards”.