Joseph Smith was of the blood of Ephraim, not through Lehi’s descendants, but from the blood of Ephraim scattered throughout the nations.
The children of a woman who has been sealed in the temple and remarries for time only and remains faithful to her covenants will be considered to have been born under the covenant, and will belong to their mother in the eternities.
The children sealed to parents whose sealing has been revoked still receive all the blessings of being sealed to worthy parents in the next life and inheriting the celestial kingdom.
Those who have made sacred covenants in the temple and live righteously will remain as families in the eternities.
Since the twelve tribes of Israel were divided throughout the whole earth, many people are descendants of one of the various tribes.
Mormons bless babies for two reasons: one is to create a record for the child in the Mormon Church, and the second is to give the child blessings and promises from God.
The Lord has not revealed when the spirit enters a body, but parents of lifeless children can be comforted through their faith in and knowledge of the merciful Lord omnipotent.
The General Authorities of the Mormon Church have spoken on the subject of bearing and raising children in families–it is the greatest blessing and privilege of marriage.
The Mormon Church makes membership records only for living members, but families are encouraged to record stillborn children in their own records.
Mormon doctrine teaches that the House of Israel was scattered and mixed with all nations, so most people have some direct lineal connection to one of the tribes.