Connect multiple VNets with one on-prem data center

Hi,

I am struggling with the design of our hybrid Azure network.

Currently I have the following networks:

ONPREM
VNet1 in Subscription 1
VNet2 in Subscription 2

What I would like to do is just have one S2S VPN between ONPREM and "Azure". Then, somehow route traffic to and from VNet1 and VNet2 trough that S2S VPN.

So far I have managed to create a S2S VPN between ONPREM and VNet1 and VMs on those two network can access each other.

I have also connected VNet1 and VNet2 and VMs on those two networks can access each other.

But what I have not managed to do is make VMs on VNet2 access VMs on ONPREM.

How would I go on an build something like that in Azure?

Regards