Share 'Il en a laissé prendre à ses enfants'

The rule for this construction says that with "faire" and sometimes also with "laisser," the subject of the verb that follows can be preceded by "à" or "par."   The first example is "Il a fait taper la lettre à (or "par") la secretaire -- He had the secretary type the letter.  The second example is "Il en a laissé prendre à ses enfants" -- He let his children have some.   I can probably learn to…