How do I put children in birth order?

Answer 1

If you add a birthdate (or at least year) they will be ordered by by that.

Edit: Alternately (this is a newish feature that I hadn't used before), it you don't know the birth years, you can change the birth order by:

1. Click on one of the children.
2. Click "Change or delete" on the left panel
3. Click "Change sibling order"
4. Now you can move them up or down in the birth order