iMessage workflow for incoming texts from someone?
You could activate the Emergency Bypass on you iPhone. 
Unfortunately there is no possibility on the mac yet. 
But it would be usable on the iPhone.


Launch Contacts from your Home screen and open the contact you want Emergency Bypass on.
Tap Edit.
Tap Ringtone.
Tap the Emergency Bypass switch. The switch should be green when it's enabled.
Tap
Done.
Tap Done again.