Child benefits can basically be paid to the children who belong to your household. A household is only if the child is constantly living in your household, cared for and educated by you and is supplied from the funds of your household.
Just the mere registration of a child with a registration office does not lead to household affiliation. During a temporary external placement for school or vocational training, an existing household membership is maintained.
More details can be found in the leaflet about child benefit.
The presence of the children and their affiliation to the household must be officially proven. This is the purpose of the reversed budget statement.
Please fill in the section
A very legible. In the section
B are your details by the competent registration authority Einwohnermeldeamt) or another public body to certify and provided with the seal of approval or service stamp.
If you have children in your child benefit claim who live permanently (not just temporarily) outside of your household, please submit a 'life certificate' (KG 3b). If such children are in education or training, a certificate of education or training may be submitted instead of a certificate of living, but not older than six months. The corresponding certificate forms can be obtained from your family fund.
Use to the following link fill the form.
https://www.arbeitsagentur.de/familie-und-kinder/kino
https://con.arbeitsagentur.de/prod/apok/ct/dam/download/documents/Bescheinigung-KG3a_ba015208.pdf