There are a few expressions for "taking care of someone" which depend on how closely you get involved. - 보살피다 / 보살펴 주다 = give someone close care, as with children, small animals, or someone weak. - 돌보다 / 돌봐 주다 = look after someone - not as much as 보살피다 but still fairly closely. - 챙겨 주다 = attend to them. For normal adults. X-를 (잘) 부탁드립니다 has a similar meaning, like "I count on you (for their well-being)". - 형/동생/아빠(를) (잘) 챙겨 주세요. (This seems the best choice in your case) - 형/동생/아빠(를) (잘) 부탁 드려요. (This is more common when you entrust someone under their care for a while)