The mileage originating with different members may not be combined. For example, Mr. Chen has 40,000 miles and Mrs. Chen has 20,000 miles. Mrs. Chen is traveling from Taipei to Los Angeles, and wants an award upgrade from Premium Economy Class to Business Class(K fare)(a cost of 31,500 miles.)
This could be possible if Mr. Chen transfers 31,500 of his miles to Mrs. Chen. He cannot transfer just 11,500 miles and use those miles plus Mrs. Chen's 20,000 to secure the award upgrade.