Youssef, Have you tried using the @mod@ format in the OLE object inside a Faceplate? Will the VB replacement code find and replace these paths when the faceplate is opened? I've only configured the embedded trend control with explicit paths in displays.
I wonder how the embedded OLE object will impact Faceplate call up times and whether the trend should only be invoked on demand. What happens if the module parameter defined in the trend is not being historized on the server. Will this affect call up time?
The "supported" access to trends is with PHV, called from the faceplate on demand, passing the module name to the preformatted PHV file for that faceplate. PHV will pull up the OPC runtime value even if the history data is not available. PHV is a separate application than Operate, so if the operator wants to continue to another display, operate is not waiting on calls to the historian.
If the MOD Substitution does work, I'd be cautious to test how it behaves when tags are not historized or the History server is not responding. This certainly would be an interesting way to manage integrated trends.