remote from Azure vm on a site to site to another VM on another company site to site

Hi.  got kind of a strange one.  we have 3 site to site VPN's set up in our firewall/router.  one is to Azure, one is to our web hosting company, and the other is to our offsite backup.  we can remote desktop to vm's through all these VPN's.  however we need to remote into a VM that's through the web hosting VPN from a VM that's on Azure.  but it ain't working.  On the VM on Azure, when we launch remote desktop it tries and tries and then errors out.  is there a work around on this?  do I need to set up some kind of gateway?