These are really two distinct questions that have interrelated answers. Broadly speaking, any family structural change, created by the addition or loss of a family member is stressful for the family. This is a universal and consistent pattern across the globe. Interestingly though, families that are most independent and value individualism are the most impacted by additions to the family structure, such as an elder moving into the household. On the other side of the issue, those families that are more interconnected and supportive tend to be most impacted by the loss of a family member.
It is critical to keep in mind that families are not simply structures, but relational and dynamic parts of a society and culture. Therefore, any changes that alter family structure will impact the relationships within them.
Which populations are most affected by change? Broadly, those that have mental or physical illness, socioeconomic problems, lack of education, impaired intellect; those who have been through trauma or are recovering from it, and those who have alcohol and other drug issues in the family... All of these conditions, and others like them, create pressure on the family by their very natures. Add change to this picture, and the hardship of that process places even more stress on the family.
From a multicultural perspective, which populations are impacted the most? Generally it can be said that the more diversity that is accepted by the culture and by the family, the easier adjustments will be. This is because isolation and stigma of gaining help is often reduced and the family flourishes even under the stress of change. Why? Because the perception of cultural acceptance is there. Simply, the family has a problem, the culture supports them.
Where this is not so, such as with a distinct minority, or an ostracized group, that acceptance may be lacking and stress is increased.
Therefore, it is not so much the diversity issue(s) that cause issue with the family, it is the acceptance of diversity as a foundation for solving family issues. The more the society is open to help diverse families, the better the stress management and openness to change and adaptation...no matter what the diversity issue is.