Moving File Systems from a Single Path Device to a Multipath

I am trying to work out how to move single path devices to multipath. the single path devices are all part of a volume group.
Our storage device is a Dell md3460 direct connected to a Dell PowerEdge server running Red Hat Enterprise Linux Server release 7.3 (Maipo).
The problem I am having is that it appears that the file system was original setup as single path. I would like to move these to multipath without breaking the volume group. Any help would be greatly appreciated.