Devils hand in the cookie jar

[6 man reef]

Need advice on a separation of a very large piece from three live rocks. I am moving this into a larger established tank and cannot make the coral/rocks fit as they are. I would prefer to cut it away from two of the rocks at it's attachments leaving it attached to it's original rock. It is quite large 10-15 inches across and 17 inches high. Would it have a better survival if I cut it into three pieces leaving a piece attached to each rock? This option would necessitate cutting through the main (body) in two areas. I have not had any experience dividing/cutting this type of coral.