Here is what I'd like to achieve.
Meraki A (spoke) -------> Meraki B (Hub) ---------------------> non-Meraki peer C
The connection as above is all good up and running, however I'd like to get Meraki A to be able to "see" non-Meraki peer site C. How can I go about it?
Any help would be appreciated.
You can't do that in the way you've shown. The routing to reach site C isn't shared across the AutoVPN, so Site A will never be able to communicate to Site C, and vice-versa.
The way you achieve it in a Meraki environment is by building a site-to-site VPN in Meraki which establishes endpoints in both Site A and Site B, and then in Site C you need to configure two VPNs, one which comes from Site A and one from Site B. The only other way is to introduce another VPN termination into the environment (e.g. a Cisco Firepower, or other firewall of choice) at Site B which terminates the VPN from Site C, and then you establish appropriate routing to/from the new VPN termination (firewall), and distribute this into the AutoVPN.
i just had the same issue recently...how i solved it...I installed on the HUB site 2 MX's. One terminating the AutoVPN the other terminateing the non Meraki VPN. Had to create 2 organization...the routing between the 2 domains a have done on the lan side of the 2 HUB MX's.
Meraki A (spoke) ----> Meraki B1 (Hub AutoVPN) <----------> Meraki B2 (Hub non Meraki VPN) ----> non-Meraki peer C