Tessa’s valid will provides as follows:

'I bequeath my estate to my sister Pam’s children.'

At the time of Tessa’s death, Pam had a daughter, Debbie, an adopted son, Shaun, and she was expecting a child, Chrissy. Pam also had a stepson, Brandon. Brandon was the child of Pam’s husband from a previous relationship. After Tessa’s death, Chrissy was born alive and Pam subsequently had two more children, Ethan and Freddy. Who inherited Tessa’s estate?