Hi,
I had two Internet connections for HQ and each branch office.
ASA injects redistributed static route to the core switch, or you can create a generic branch office subnet(10.10.0.0/16) toward ASA.
Then create more specific static route (10.10.10.0/24 for Branch A, 10.10.20.0/24 for Branch B) to Meraki whenever you switch over onto it. That how I did for 80+ branches.
However, if I could do it again, I would set up a MX100 on a transparent mode so that I could use OSPF.