Friends of hers have been leaving messages on her page.
One friend, Chloe, wrote: "I can't belive that one of the bodys was your mam. RIP Jill Foster. I hope that the other body isnt your dad."
Another friend called Lucy added: "Forever in our hearts, once there forever in our lives."
Kirstie's head teacher at Ellesmere College Brendan Wignall said it would be "inappropriate to comment" at the moment.
In a statement, he said: "We are awaiting confirmation of identity from West Mercia Constabulary; despite the obvious speculation, I feel that it would be inappropriate to comment further until facts had been confirmed by the authorities.
"We are all deeply concerned about this latest development in the ongoing investigation."
Special prayers for the family were held on Sunday at Maesbrook Parish Church.
The Reverend Prebendary David Austerberry said the local community had been "bewildered and stunned" by what had happened.
Det Supt Jon Groves, of West Mercia Police, said the search and examination of the property could take weeks.
He said: "I am grateful for the continued support of those living in the area.
"Our thoughts remain with the families of Chris, Jill and Kirstie Foster and we will follow up every possible line of inquiry to establish what happened at Osbaston House in the early hours of Tuesday."
Flowers have been laid near the scene, including some from one of Kirstie's friends with a note saying: "School will never be the same without you."
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