Hi Robert, ah thank you, but unfortunately not, because of what I wrote about the reason we cannot rely on the state of the ticket: 

“We can’t use the incident state though, because tickets can be passed between family and non-family without the state changing.”

so for example, if our service desk have the ticket first (state=new) and they work on it, they will set the ticket to “in-progress”. The ticket might then be reassigned to the “family” if the desk can fix it. Unfortunately the state of the ticket does not automatically change to “new”… therefore the SLA start condition would not be met. I think this is normal out-of-the-box behaviour,

sincerely

CMH