cust_local = 'Ground_Ctrl'
cust_global = 'Root_Ctrl'
# Performs function that snaps global control to local
sel = ":".join(cmds.ls(sl=True)[0].split(":")[:-1])
locTrack = cmds.spaceLocator(name=sel + "_snapPoint")[0]
cmds.parentConstraint(sel + cust_local, locTrack, mo=False)
cmds.cutKey(sel + cust_local, sel + cust_global, cl=True,
            at=["translateX", "translateY", "translateZ", "rotateX", "rotateY", "rotateZ"])
cmds.delete(locTrack, cn=True)
cmds.parentConstraint(locTrack, sel + cust_global, mo=False)
cmds.parentConstraint(locTrack, sel + cust_local, mo=False)
cmds.delete(locTrack)