When another verb or subordinate clause is a direct object, a very special verb is in play. In Sindarin, such verbs are usually conjugated as intransitive verbs.
The verb-phrase acting as the direct object is NOT lenited.
There are two things to take into account.
1. The second verb of the compound is the direct object. It will be in a noun-like state, called a gerund, and it can't hold any information about when the action is happening or who is doing the action. That information is found only on the first part of the compound predicate.
I'm demonstrating this with aníra- "to want" and the impersonal verb (m)boe "need/must/ it is necessary."
Aníron linnad. - I want to sing.
Boe linnad. - It is necessary to sing. (One must sing.)
If the second half of the compound predicate has a subject, that subject is dative and marked with an.
Aníron añ Glaewen linnad. - I want Glaewen to sing.
Boe añ Glaewen linnad. - It is necessary for Glaewen to sing. (Glaewen needs to sing.)
If the indirect object is a dative pronoun, you can treat it like it's an accusative pronoun, just the same as you would with an intransitive verb.
Aníron anlen linnad. - I want you to sing.
Len aníron linnad. - It is you who I want to sing.
Boe anlen linnad. - It is necessary for you to sing. (You need to sing.)
Boe len linnad. - It is necessary for you to sing. (You need to sing.)
2. The direct object and indirect object of the second verb act the same as they would normally. Whether they are nouns:
I aran aníra maded 'lî. - The king wants to eat honey.
Anin aran boe maded 'lî. - For the king, it is necessary to eat honey. (The king needs to eat honey.)
Or pronouns:
Aníron gi ndaged. - I want to kill you.
Boe annin gi ndaged. - It is necessary for me to kill you. (I must kill you.)