Adopting and Disowning

Adopting:

(defun insert-child (parent child position))
(defun insert-child-after (parent new-child ref-child) ....)
(defun insert-child-before (parent new-child ref-child) ...)
(defun append-child (parent child) ...)
(defun prepend-child (parent child) ...)

Disowning:

(defun delete-child-if (predicate parent &rest args &key from-end start end count key))
(defun delete-nth-child (idx parent) ...)
(defun delete-child (child parent &key from-end test start end count key) ...)
(defun delete-children (parent) ...)

In one step (for well-formedness):

(defun replace-child (parent new-child old-child) ...)