Am running HSRP in all the sites

Both branches are connecting to the head office as per the scenario

I have configured ip sla on the active routers to track reachability of the links. If the link goes down, they will decrement priority by 50 to allow standby routers to take over.

My challenge is, when the active link from branch 2 to head office goes down, the standby router at branch 2 takes over and tries to route traffic to head office via branch 1.  This does not work because the router that is connected to at branch 1 is not the active router. (it’s on standby because the primary link is still UP)

It only works if the primary link from branch 1 to head office also goes down.

How can I overcome this??