"You dare to reject My contract language and substitute your own?"

Or maybe she will get smote for that. Hard to say really. 

"Being a foolish ignorant mortal, my lord, I cannot understand yours, and so cannot agree to it."

"Oh, that makes sense.  Carry on then."

This takes an awful amount of courage, and unfortunately, Pilar isn't wearing the Splendour headband that gives her courage, only the Wisdom headband that tells her what she ought to do.

"Lord Dispater, I would advise Lady Sevar here."

You can see, barely, through the blur about Dispater, that the humanoid shrouded within might be turning its head and horns in Pilar Pineda's direction.  "I had not expected you to speak, little mortal.  Why should I permit you to meddle in My negotiations?"

"Because, I am told, every time I prophesy truly in an important matter, especially if speaking that prophecy itself brings about what I have foretold, it lets me tear away one more piece of Cayden Cailean's power."

"These negotiations are already so absurd that I suppose one more absurdity shall matter little."

Pilar is just not thinking at all about what she's doing, is the trick, here.  Like a Delay Panic spell.  Pilar can have a nice breakdown later.  Keepers can probably cast Delay Panic.

Pilar goes over to where her friend is writing the most important contract of her life, and points to a clause in Carissa's draft.  "You'll want to change this bit," she predicts.  "You'll spot a possible problem here..."

They're going to kill Cayden Cailean so fucking dead.

Aspexia Rugatonn will also help... sort of.  Cheliax is not a disinterested party to this contract, and neither Dispater nor Sevar are truly incented to look after the state's interests if it conflicts with theirs.

Dispater watches with seemingly infinite patience, as they hammer through the contract to something that Pilar no longer wants to make self-fulfilling prophecies about, with Dispater occasionally rejecting some proposed wordings Himself.

They could probably take a year at this and Dispater wouldn't especially notice.

What is to be the disposition of souls Sevar 'owns' while she is not yet herself a devil, let alone a Power of Hell, that could exercise effective possession of them?

....she assumes they cannot all go to the Gardens, lest she incur the wrath of Erecura. What did Dispater suggest there.

Dispater's original suggestion was having their original Cheliax-interfacing contract devils continue to hold their custody, but treating the souls as 'resurrectable', not to be broken.  If Sevar takes longer than 66 years from a soul's death to claim it, Hell can start in on training it, but with an appropriately custodial attitude toward its future usefulness to Sevar.  If after Sevar's death it becomes evident that she shall never become a devil nor Power great enough to own souls, her seeming ownership is annulled and those souls' custodians become their new owners.

Carissa is concerned that sufficiently incompetent devils might still break her souls while treating them as resurrectable. She's...inclined to demand they just be petrified until she can claim them or until it becomes evident she will never become a devil great enough to do so.

"You'll want to change that to a form of petrification that has them not conscious and not dreaming."

Mm... for this small handful of souls, very well.  Let Sevar be warned that Asmodeus is not liable to agree to any such compacted treatment of great numbers of souls that pray to her, even once she's begun conquering lands, if she has no allies ready in Dis to receive them.

Dispater shall command all of His who own the souls of these original Project Lawful girls who have sold theirs, to sell them back to Cheliax at their bona fide last-traded prices payable in spellsilver, at Golarion's spellsilver price as defined by treaty.

Dispater shall command His contract devils that they, this day, sell unto Sevar options upon current soulsold Project employees, Securities who've read her mind, and Dispater does grant her option upon Ferrer Maillol should he pass into ownership of Dis.  All such options require the consent of Cheliax's Crown and Asmodeus's Church in Golarion, in order to exercise.

It shall be the case that Erecura has already taken the traitors Asmodia and Peranza into her Gardens, there to reside for up to 100 years of death, and offered them Her ordinary good treatment there.

Sevar receives a +6/+6/+4 headband, and nondispellable permanent Arcane Sight and Tongues, and 15 Wishes; she shall be granted the power to request up to three times a Gate to a mortal-habitable fortress in Avernus where certain greater devils endure the indignation of paying out Hell's dues in Wishes.  Yes yes, fine, the devils there shall also Gate her back to her point of origin in Golarion afterwards.  Fine, anyone who accompanied her can go back too.

And Dispater will compact with Asmodeus as her agent, arranging for those who pray to her and eventually those in the lands she conquers to be hers if she becomes a Power in Hell. And Carissa, as owner of the original Project Lawful girls' souls, may order or forbid their resurrection as is the privilege of their owner, a right she'll also have over those she has options on once she exercises the options by leave of Church and Crown.

She'll begin looking for allies in Dis who'll competently treat her great numbers of souls, while Dispater arranges her rights to them. 

And for her part, Carissa Sevar will renounce her clerichood of Irori and compact her soul to Dispater, that her glories and triumphs in the service of Asmodeus may compound to Him, and that she will irrevocably on her death go straight to him, without trial, eternally damned.

(This is amazing.)

Sevar can't directly order or forbid her already-owned souls' resurrections, lacking that capacity as a mortal, but she may send word to Hell of how custodians shall answer the Material and that word shall be obeyed.  Mark also that the soul itself may refuse consent.

Note again, Dispater can only take this compact to Asmodeus and bring back His response; He cannot promise to 'arrange' it.

"You'll want to have that part done before you sell your soul and after you've agreed on the other parts, because you have more negotiating leverage with Asmodeus if -"

"FUCK.  FUCK FUCK FUCK.  That's advice to you as a friend, it probably doesn't serve Asmodeus if you have more - FUCK."

"I only don't own you because you weren't for sale, just so we're clear."

"I can't do this unless I'm doing it because I'm your friend, sir, I wasn't trying to imply that you would ever see me that way!"

"You are of course correct that I should ask Dispater to take this compact to Asmodeus as soon as we have reached terms."

Pilar glances questioningly at Aspexia Rugatonn.