One of them has lost her husband, killed while fighting for the Islamic State in Syria.
Saima Akter Mukta and Rabeya Akter Tumpa, daughters of late Soleman Sheikh from Gopalganj's Tungiparha, have been missing for years, a highly placed source in the government says.
Mukta and Tumpa were married to Saiful Haque Sujon and Shariful Haque Emon, sons of AKM Abul Hasnat from Khulna, respectively.
Mukta's husband Sujon died in an airstrike on an Islamic State den in Syria in 2015, Tungiparha Police Station OC Md Mahmudul Haque said.
Police later arrested Sujon and Emon's father Hasnat at Karwan Bazar in Dhaka on charge of financing terrorism, the OC said. Hasnat is now in jail.
The police officer said Mukta and Tumpa's relatives in Gopalganj and in-laws in Khulna have not been in contact with them for years.
According to the security forces, Sujon's last known address is a house beside Iqbal Nagar High School in Khulna while Emon's is beside the Intellectuals Graveyard in Dhaka's Mirpur.
No-one residing in the areas knows about them.
No member of Mukta and Tumpa's family was found in their Tungiparha house either.
Their uncle from the extended family, one Asad Sheikh, lives in the house now.
His wife Beauty Begum told bdnews24.com Soleman did business in Khulna and raised his daughters there.
One Bayezid Mia, a neighbour of Hasnat in Khulna, said everyone in the area knows that Sujon died in a Russian airstrike in Syria last year.
Some locals said Soleman donated a piece of land for a madrasa 15 years ago.
Abul Khayer Hawlader, the general secretary of the madrasa's managing committee, said he was not sure whether Soleman's children had become militants.
"But I've heard that one of his sons-in-law died in Syria," he said.
"Mukta and Tumpa may have gone to Syria with their husbands," he added.
The source in the government said the two sisters had been in the UK with their husbands.
They later went to Syria, where Sujon died.
He could not confirm whether Mukta and Tumpa are in Bangladesh or in Syria now.
Four more missing
Besides the Gopalganj sisters, four other are missing, according to the source.
They are former secretary Musa Sadiq's son Saimun Hasib Monaj from Banani in Dhaka, Md Ridwan Islam Tuhin from Gazipur's Sreepur, Abdur Rahman Masud from Ashulia and AKM Takiur Rahman from Bogra.
Monaj left home for Malaysia a week after his marriage two years ago, the caretaker of his house Forman Ali told bdnews24.com.
His wife left the house 10 to 15 days later, he added.
"He was a very good boy. He said prayers regularly, grew some beard, always kept his head down and talked less," Ali said.
He said Monaj's father Musa did not live in the house with the holding No. 23 at Road No. 22.
Musa lives in another house in the area with his second wife, the caretaker said.
"He seldom comes to this house. His eldest son Mehmood and his mother Hosne Ara Joyce live here," he said.
Mizanur Rahman, the caretaker at the other house of Musa, said the former secretary would not speak to any journalist.
Tuhin from Gazipur, who graduated from the Dhaka University's computer science department in 2013, has been missing for one and a half years, his brother 'Tanim' told bdnews24.com.
Tuhin took a job at a private company after graduation.
But he left the job and started working as Samsung mobile-phone company's software engineer at its Karwan Bazar office.
"He suddenly disappeared. His mobile phone was switched off," Tanim said.
He said he had also filed a general diary at Kalabagan Police Station informing the law enforcers about his brother going missing.
Ashulia Police Station officials said they knew nothing about Abdur Rahman. They were making a list of those gone missing in the area.
bdnews24.com could not find the house at the address of Abdur Rahman.
Bogra's Takiur Rahman's address was provided as a nine-storey building at Kalitola.
bdnews24.com found the building under construction.
Source: Bangladesh's First Internet Newspaper