Gotta love banks !

It was probably already crossed.

Not quite the same situation as yourself. But I did have one occurrence  with CBA on a similar topic. I was selling a property (that had been purchased with 20 percent deposit) about 10 months ago.  I had other properties with cba. All of them are not crossed together (always always took out a separate loan with a 20 percent deposit.) I'm 3 weeks from settling and they tell me they need to come around and value my other properties. I asked them why they needed to do that. She told me they were cross collateralised. I told her they most certainly are not. She better get her manager and tell me why CBA have CC'd my assets whilst my loan documents specifically say they are stand alone. They (cba) back tracked very quickly in that conversation (also got another year free on the wealth package for that one). You never know what they are doing behind the scenes and sure they prob could get the other properties if I defaulted. But not before they took the property I defaulted on first. 

Btw I have noticed though. A lot of the times when I purchase property with CBA if I tell them what my other properties are worth they would put that into the system as a desktop. (The system has a medium house price for each suburb and depending on what you listed the value of your property at will say if it requires a desktop valuation, drive by or full valuation. And specifically your house might be worth 350k. But by putting in 360k,370k (opps changed to a full valuation) drop back down to 365k and it's back to desktop.

Then when you sell with CBA they go… Full vals on everything they are not sure about. 

They are prepared to load the additional risk if you are giving them business but not if thy is taken it away.