Dear Karim,
If you want to repeat a set of questions with ODK2 (for example, ask each household member their name and age), you will basically design two surveys, one the “main” (household) form and one the “subform” (individuals). You link them with a “query” that uses linking variable(s), for example, the household id.
The documentation for queries is here: Using ODK-X XLSX Converter — ODK-X Docs
And we did an example in these training materials:
The 10_ slide deck, part c. (solutions are online there as well).
Hope that helps!
Best,
Caroline