You may need to re-post your question--something must have dropped out in typing it, since there is no actual indication of what you are wondering a "healthcare application" can or cannot do or include.If you were asking whether the application can ask if the applicant is related to the client, then yes--that is legal. An application may ask any information which (1) is not specifically made illegal to ask; and (2) is possibly relevant for either  health care or business reasons (e.g. to deter fraud). Knowing of family relationships is relevant to establishing eligibility for coverage in some cases, or often for determining is there is a possibility of a conflict of interest or self-dealing.If this does not answer your question, kindly re-post it with additional information.