Where notices to treat have been served for the acquisition of the several interests in any land then, if the acquiring authority so desire, the disputed claims of the persons entitled to those interests shall, so far as practicable, be heard and determined by the same member or members of the Lands Tribunal, and the Lord President of the Court of Session may make rules under the Lands Tribunal Act 1949 providing that such claims shall be heard together ; but the value of the several interests shall be separately assessed.