I think I read Cap's words to Rosa as gerrieb, above, did. He was advising her not to take on the role of an adult but to rely on those older and wiser above her to help out. Ultimately, in most difficult situations someone does take charge, and it is regrettable when that role has to be born by a child. Rosa is the oldest child and this is a role the first child often claims. In this situation, Rosa committed herself to doing so to her mother. While she is trying hard to look after her siblings and is a very caring and committed older sister, I think her family is working to keep her from bearing too much of the responsibility.