The mob smashed windows and called on the girls' families to leave the Penywaun estate, in Aberdare, West Glamorgan, on Monday. Maria Rossi and Christine Molloy had earlier been charged with the murder of Edna Philips, 70.
Later on Monday night more than 50 police evacuated the two families to an undisclosed destination for their own safety. Yesterday the houses were boarded up and police were on guard outside.
Police last night escorted four more of the girls' relatives from the estate after their homes were pelted with eggs and stones by a crowd of 50 residents in a new outbreak of disorder. A total of 13 family members and relatives have now been taken to secret addresses.
The self-styled vigilantes moved in after Ms Philips, who lived alone on the estate, was found brutally murdered at the end of last week. She was said to have been stabbed more than 20 times.
Maria Rossi lived next door to the spinster and Christine Molloy in a neighbouring street. Police arrested them on Sunday. On Monday, they were charged with the murder and remanded in custody for 10 days by local magistrates.
Witnesses said a crowd gathered outside Maria Rossi's home in Dan Yr Heol, making threats and throwing stones and bricks. Later the crowd moved to ChristineMolloy's home in nearby Haulfryn.
One local resident, Alison Moorcroft, said yesterday: 'Feelings are running very high on the estate after the death of Edna. Protesters moved from outside one house to the other and did the same in both places.'
Last night Supt John Millett appealed for calm after the arrests. He urged people 'not to do anything which might interfere with the investigation or the course of justice'.