SDWAN interface at HQ vs Branches

[vlw38]

In planning stages:SDWAN implementation.  

HQ: (2) Fortigates in HA  (1) MPLS interface and (1) ISP/wan1 interface

Branches: (6) Fortigates, (1) MPLS interface and (1) ISP/wan1 interface

I understand I need to create SDWAN enabled interfaces/members, default routes, etc on branch Fortigates... 

Do I need to also create SDWAN interfaces/default routes etc on the HQ Fortigates?

[sw2090]

You will always need to have at least one default route at least on the FGT. This is needed for internet access and to enable the FGT to reach the Fortinet Servers to get license statuses and virus definitions etc.

sd-wan is bascially only needed if there is more than one internet line connected to the FGT and you want it to do load balancing with them.