Hello @Grzesiek2010, hello @Maya,
We hope this delete behavior will be changed soon in the new release.
The workaround is only hiding the grouped data, but the repeat itself still exists, also position(..). So you will have mismatch and problems when you use count(repeatGroup), position(..) and following references, like education details in a following repeatGroup for the HH members in the first repeat.
See also https://community.kobotoolbox.org/t/dynamic-repeat-group-does-not-work-properly-if-the-number-of-repetitions-is-updated/10353/3