Call Queues: allow mixture of call handling (simultaneously and in fixed order)

In a particular extensions call forwarding section (home, mobile, office), you can set the phones to ring simultaneous or in a fixed order. You also have the ability to group certain numbers such that home + cell ring simultaneous for 4 rings, and failing that, it goes to office numbers.
Now let's talk about Call Queues. The options are simultaneous (to all members), round-robin (to all members), or fixed order (to all members).
What I want is to have a call queue ring our call center first for four rings. They should answer 95% of the time within a ring. But failing that, I don't want the call to go to voicemail. I want it to "escalate" to a level 2 engineer (there are 9 of them). So I created extensions for each of their cell phones. So the call queue has 10 members (the call center extension + 9 extensions for the nine engineer cells).
The trouble is that if I set the Call Queue to simultaneous, all extensions (call center + all engineers' cell) ring at the same time. If I set it to fixed-order, the call center rings first (good!) but then engineer #1 gets any calls after that. Engineer #2 wouldn't be attempted until 4 rings of engineer #1 cell first. This isn't good customer service at all.
What I would like is the "grouping" feature, such that I could set the queue to try the call center first, and then failing that, simultaneously call the 9 engineer cells.
I've tried to nest groups within groups, so that after trying the call center, the first call queue forwards to a second call queue that has all the engineer cells set to simultaneous. But that isn't allowed.