iptables: forward packet to another network

I have two machines on 2 different networks which are interconnected.

First network:

• 10.0.0.0/24

Second network:

• 10.0.1.0/24

The first network is running an OpenVPN under 10.0.0.10 with ipv4_forwarding enabled.

The second network is running a bastion server under 10.0.1.20 with ipv4_forwarding enabled.

The second network has a routing rule to access some S2S with this range: 10.1.0.0/16

I'm trying to figure out how can I receive packets on the OpenVPN client that will be forwarded to the bastion server and from there to the S2S only when the packets are actually heading towards this specific range (10.1.0.0/16).

Do I need to alter the iptables on the bastion server or forwarding is sufficient?

Thank you very much :)