Answer given in the comments to the orginal post. Posting here as an answer for easy reference:
Actually, your example IDs are bad. More likely they are like this: ABC="123456", PQR="789012", XYZ="987654"
Try this:
Assuming your data element is called "Facebook pixel ID".
Then in your rule(s) where you need to fire a Facebook pageview pixel, your actions would be like this:
First action: Core > Custom code
_satellite.setVar("Facebook pixel ID", "123456") // account ABC
Second action: Facebook > Send Page View
Third action:
Core > Custom code
_satellite.setVar("Facebook pixel ID", "789012") // account PQR
Fourth action: Facebook > Send Page View
Fifth action:
Core > Custom code
_satellite.setVar("Facebook pixel ID", "987654") // account XYZ
Sixth action: Facebook > Send Page View