I am not an expert but have been using dual and triple screens for a while.
Not all graphic cards will work together there was maybe still is a MS site which lists compatible cards.
I would give it a try.
With three screens I find I mainly use the middle screen for the work in progress and the other two for reference - icons - pages to read - graphics I am not working on.
The main/middle screen would have your most powerful card attached as the other screen(s) do not have the call for quick response.
I use 3 @E2403WS 24inch - quite pleased - no bad pixels.
What is your 26 inch and do you like it?