Security fabric with two sites

Hi,

I do have two main sites. Each of then has its own 2 ISP internet connection and I have connection between those two sites. I am planning to install Fortigate devices in each site (one for edge, one for office and one for servers). Now question is - should I configure two security fabric - one for each site or should I create one security fabric.

If I create two security fabrics can I add same FortiManager and FortiAnalyzer to both or do I need separate ones

If I create one security fabric which device is root and can I have two different devices in one fabric connecting to internet