How to disable the Your Remote Desktop Services session has ended dialog when switching between VPN

Background:
We have a few hundred clients all different networks with a VPN connection to each.
We have embedded a phonebook which only has two entries - VPN1 and VPN2
Our VPN connections are configured like this:
A clients primary site is configured to use VPN1 and other sites they have are configured to use VPN2
in the General tab, we enter the address for the VPN in the RAS phone number field
in the Events > Before Connect tab, we run the command C:\Windows\System32\rasdial.exe VPN1( or VPN2) /disconnect
This way we do not have to manage a phonebook.
Whenever we connect to a VPN, the current connection is dropped and we are connected to the required VPN.


Problem:
We want to keep existing tabs open and to be able reconnect to the relevant VPN the simplest way possible.


I have managed to get the tabs to stay open and disable the autoconnect if connection is dropped however when we connect to another clients VPN we get a dialog box - Your Remote Desktop Services session has ended.
Obviously I am aware as I ended it. Is there an option somewhere I can set to disable this dialog box.


The other issue is that after I press OK the tab goes blank and I get a Connection dialog. Quite often I open a window on the host machine and would like to refer back to it perhaps to check information on the screen. Rather than either having to take a screenshot or keep reconnecting the VPN and RDP is it possible for RDM to freeze the display regardless of losing the connection to the machine.
If not can I ask for that feature please.


Thank you.


Paul