In the summer of 1267, she was put in charge of educating false Ciri, a young girl who was handed over in place of the real one. However, when Stella formally presented the young girl to the emperor, she immediately recognized the feigned smile on Emhyr as one that would send heads rolling, though thankfully this wasn't directed at her. Instead, Stella and false Ciri were sent to Darn Rowan until "the arrival of more peaceful, happier times" though this was actually to buy time until they could locate the real Ciri.
At one point prior to being put in charge of Ciri, Stella became indebted to Fringilla Vigo and thus, when the sorceress asked for a lock of the girl's hair, Stella had no problems with sending her a small clipping, which Fringilla then used to prove to herself that it was indeed a false Ciri.
Early the following year, while still in Darn Rowan, the emperor visited to talk with her and false Ciri, who Stella now knew wasn't the real Ciri but still took it upon herself to teach and went so far as to try to protect her. However, the emperor praised the countess for her work and after talking with false Ciri, let them both stay at Darn Rowan for the foreseeable future. A short time later, Stella later arrived in the city of Nilfgaard with false Ciri and Emhyr decided to marry the young girl to secure Cintra as part of the Empire.
Stella ended up outliving both Emhyr and false Ciri and died in 1331, leaving her estate to distant relatives.
Effenberg and Talbot,
Encyclopaedia Maxima Mundi, vol. III