Virtual Server health checking across multiple DC's for F5 DNS

I need some reflection on a configuration question which might be basic configuration but i'm just not sure.

Setup Details:

• 3 F5 DNS appliances each in a separate physical datacenters user for GeoIP based DNS loadbalancing
• Synchronize DNS configuration between appliances via iQuery (used bigip_add command on all units)
• Serves multiple Wide IPS 
• Each DNS appliances resides in its own 'datacenter' within the F5 configuration and is monitoring various destinations (Virtual Servers) which are not specifically bound to the same datacenter (so in theory F5 DNS in Datacenter C can be down while its configured Virtual Servers are NOT)
• No LTM's involved

Configuration of F5 DNS:

• Datacenter A - Server A (F5 DNS) - Virtual Server A1,A2,A3
• Datacenter B - Server B (F5 DNS) - Virtual Server B1,B2,B3
• Datacenter C - Server C (F5 DNS) - Virtual Server C1,C2,C3,C4,C5,C6
• Wide IP W1 is responding with either A1,B1 or C1 based on Request GeoIP location and availability of the virtual server. The same applies to Wide IP W2 and W3 while W4,5 & 6 are only responding with a single device C4,5 or 6.

My Questions:

• If Server C goes down, will Server A or B take over (eg. Inherit) health checking for Virtual Server C1//5 which are used for Wide IP W1 till 5 ? Or do I need to Configure all my Virtual Servers in each Data Center (and F5 might determine which DC is best equipped for actual health checking) ?
• Given the simplistic configuration I have is it advised to keep the appliances in a sync group or keep them standalone and configure each unit on its own? (I think I know the answer :-))

Any advice is welcome, thanks.