Linux: how to implement routing between networks on the same interface?

Question

linux

There are 3 objects, each with its own subnet. A: 10.200.0.0/24, B: 10.200.1.0/24, C: 10.200.2.0/24.
There is L2 vpn from the provider in each of the 3 objects. It has a subnet of 10.2.2.0/24. A: 10.2.2.1, B: 10.2.2.2, C: 10.2.2.3.
Each of the objects has a router based on a basin with Linux (mips). Routes to other subnets are registered on each of the routers (and the default route is through office A). As it turned out after purchasing the service, VPN has its own peculiarity - the architecture is not fully connected, but point-to-point, i.e. traffic goes between A and B, A and C, traffic does not go between B and C, which was later confirmed by the provider.
Is there an option to force traffic between B and C through router A without reconfiguring vpn from /24 to 2 networks /30 from A to objects B and C? The objects are far away, and it is not advisable to change the settings remotely.

Answer 1

Just write routes to networks 10.200.1.0/24 and 10.200.2.0/24 on router A.

routerA# ip route
10.200.1.0/24 via 10.2.2.2
10.200.2.0/24 via 10.2.2.3