This question is a result of not understanding hmong culture. First of all, culture changes, n we cant say what is truly original anymore. Secondly, we cant say that since a certain group does thing a certain way, then it means that certain group have always done that way.
Regarding the elderly name, from what i know, all mong that came to present day Vietnam southward do need to call the husband to come n give the name. However, keep in mind that moob leeg moved southward first...n because of this, they are separated from the bigger group first. This migration resulted in leaving inlaws back in china or leaving them in other parts of the country. This is the main reason y moob leeg do not call the inlaws anymore...with the problem of distance being the main culprit. After one generation, it becomes a tradition. People who do not know the history of thw culture would say that white does this n leeg does that...but the truth is that mong that moved south from china all did one thing....n that is...to call the inlaws.
Regarding the people in china, not sure how they evolved. So the answer to the question is...it doesnt matter how you do it....it us still the same tradition.