I admit to being a complete newbie when it comes to networking but isn’t the whole idea of a VPN to secure and isolate your network from everything else apart from the tunnel it passes through (which I assume cannot be controlled in a commercial VPN like the one you are using). If what I am imaging a VPN to be like is anywhere near true, then I think that we you are wanting to do should not be achievable simply due to the separation that VPN would force you to create.