A kit is for modification of a horizontal valve tree to facilitate pulling of the valve tree without first having to pull a connected upper well completion having an original, first tubing hanger in a center passage in the valve tree. The kit has a tubing hanger top, a second tubing hanger and a tubing hanger adapter. The tubing hanger top has communication paths corresponding to communication paths in systems arranged downstream in or by the valve tree. The second tubing hanger has communication paths for communicating with downhole installations in a well. The tubing hanger adapter has devices for coupling the tubing hanger adapter with the tubing hanger top and the second tubing hanger, and communication paths for coupling the communication paths of the tubing hanger top with the corresponding communication paths of the second tubing hanger. A method is for modifying a valve tree via the modification kit.