Dear @Katjakatja,
Welcome to the Wefugees Community and thank you for your question.
If I understood correctly, the married couple/the parents are the only members (i.e. no minor children etc.) of the "Bedarfsgemeinschaft" ("community in need" or community of dependance") and as such calculated commonly as one "unit" by the Jobcenter, right? To be sure about the calculation, one need to have a **** at the Jobcenter's "Bescheid", but I assume it is rather unlikely to be officially "in need" of social money if someone working full-time with minimum wage (roughly earning around 1500 EUR after tax), "only" has to cover the costs of two people and has not even to pay rent.
If you guys have doubts about the Jobcenter's calculation, you may see a social counselling ("Sozialberatung") or migration counseling office - the social workers can help you to check it.
In any case, please also don't hesitate to get back to us with any further questions.
All the best,
Meike