<em>I know my previous answers didn't help you, I hope to help you now. </em><em>:</em><em>)</em>
Yo lopreparo.
Yo los compro.
Dolores las hace.
Juan lostrae
Yo losinvito.
To replace the accompanying noun, write a direct object. They can be replaced if it is masculine it is "<u>lo</u>" (singular) or "<u>los</u>" (plural) and if it is feminine it is "<u>la</u>" (singular) or "<u>las</u>" (plural).
<em>Note</em>: I think that section 2 and section 3 must remove the verbal periphrasis; stay with the conjugated verb.