Possible Clues:

• Stress rate of progress accepted by each sibling
• What '!' provides
• Hip seams split under stress
• Stress or significance
• Special importance or significance
• M for a little sister, by the sound of it, that's stressed
• Stress apparent when entering Tennessee port miles away
• Force hemp to be unravelled by a half-sister
• Misshape's twisted by stress
• What the Member from the East has is a certain force