You have different PLCs that provide a web HMI?
But maybe you also have a device that can be operated over VNC protocol?
VNC can duplicate a desktop to a remote client connected over a TCP/IP network.
The SpiderControl Automation Browser now has a built-in VNC client, which means you can mix URLs that point to HTTP servers with links that connect you to a VNC server, enabling end-to-end navigation between different HMI sources.