What is a good way to display a list and editable list item on a detail page?

I have detail pages that are kind of like the attached image. An "entity" might have 1-15 children. Each child can be edited. You can also create a new child.

I can think of two ways of presenting this, one is the way in the attached image. But because it's inside a tab, I'm not sure if this counts as tabs within tabs. The other way is an accordion, which I don't like because it would be a lot of scrolling if there are 15 children. Maybe either is fine and just needs to be used based on number of children an entity has? Maybe neither is fine? What is a good way?