The victims, named by police as 49-year-old Elizabeth Edwards, originally from Edinburgh, and her 13-year-old daughter Katie, were found at the property in Dawson Avenue, Spalding, on Friday afternoon.
Lincolnshire Police have appealed for anyone who saw any suspicious activity near the victims’ home to come forward.
Speaking on Sunday, Detective Chief Inspector Martin Holvey, of the East Midlands special operations unit, said post-mortem examinations had not yet taken place to determine the cause of the deaths.
He added: “I still need to speak to anyone with any information that might be relevant from Dawson Avenue from around noon on Wednesday April 13 to noon on Friday April 15.
“If you saw or heard anything that you thought was suspicious or unusual I’d encourage you to get in touch as soon as possible.”
Meanwhile, relatives of the victims paid tribute on social media sites - with a teenage friend of Katie describing her as being “like a sister” and Ms Edwards as a second mother.
Ms Edwards’ partner, Graham Green, wrote on his Facebook page: “My babe has gone but you will always in my heart forever and ever and ever.”
Both of the teenagers accused of murder are due before magistrates in Lincoln on Monday.