As fun and delicious as that sounds, the healing salve has a limited capacity for healing and must be applied directly to the wound... even if it could be absorbed through the skin like some oil... spending a given amount of charges would then just split the effects between the two ladies, it wouldn't double them (spending 4 charges wouldn't heal 4 on both, only 2 on each). Of course the split wouldn't have to be 50-50% If only there was a way to determine who has a larger...skin surface to absorb the ointment.