The family would have known the significance of any addresses right from the beginning.
Wasn't it posted somewhere that police officers were focusing on 'other people' who may have been in her home the day she went missing?
If the crime scene actually started at her father's that would explain the intense searching there.
And maybe give a really really horrible clue as to why he posted *that* post on facebook.
You're right I think. He may have been appealing to Shauna...little knowing she would side with the killer.