The simplest procedure in such a case is to combine relationships in a single individual, and the most self-evident person to select for the dual capacity is the husband of the eldest daughter.
This is the course pursued.

Some worthy young man is secured as spouse for the senior sister; he is at the same time formally taken in as a son by the family whose cognomen he assumes, and eventually becomes the head of the house.

Strange to say, this vista of gradually unfolding honors does not seem to prove inviting.

Perhaps the new-comer objects to marrying the whole family, a prejudice not without parallel elsewhere.
Certainly the opportunity is not appreciated.

Indeed, to "go out as a son-in-law," as the Japanese idiom hath it, is considered demeaning to the matrimonial domestic.