Nepal123.com - 5

I am writing a grant to go to nepal and conduct mental health assessments for returned migrant workers, as I understand there is limited support currently available. In order to do this I am constructing a questionnaire and have seen in many other places asking survey takers to identify their caste/ethnicity however they tend to group them in different ways. I have seen the following examples:

1) Brahmin/Chhetrri/Thakuri

2) indigenous group

3) Dalit/ Minor group

4) Terai origin (madhesi/Tharu)

I have also seen it grouped in this way:

1) Brahmins/Chhetri
2) Others

I have also seen this way:
1)Brahmin/Chhetri/Thakuri

2)Dalit and Janajatis

3) Dalit, janajatis, and other Terai

4) Religious minorities

This is just a few examples but I would really appreciate someone explaining to me the thought process behind the certain groupings, what they mean, and suggestions of the best way to approach it. Thank you for your help!