In Datong, Shanxi, there is indeed a custom of seeing in-laws before marriage. This custom is called "going to court". Before marriage, the man's family will go to the woman's house to propose marriage to their parents. In this process, the man's family will bring some gifts.

As for the annual money and rice and flour money, they are usually given to the woman's family as dowry. Lucky money is a sum of money given by the man's family to the woman's parents to show their gratitude and respect. Giving rice and flour to the woman shows that the man has the ability to support his family.

As for the woman's children, when they get married, the man's family will give her children some small gifts or red envelopes to show their concern and love. This is also part of the meeting ceremony, which means that the man's family will wholeheartedly accept the woman's family and children.

It should be noted that the customs of different regions and different families may be different, so it is best to consult relevant local customs for the actual situation.