"I refer of course to a powerful orcish warlord. He has offered me many favors in exchange for obscure lore, and will gladly do so again," you explain, hoping to placate your elder sister. This is in fact mostly true. While 'many' favors is a liberal interpretation of the facts, it is at least true that you were able to leverage a tidy sum of treasure from him in exchange for some old dwarven charts of the local Underdark and a history lesson. Cajoling him into going along with your scheme would be no easy feat, although-

"Summon him," demands Vierna incisively. You shake your head. "He is no simple mercenary captain, Matron Mother. The warlord to whom I refer is mighty indeed, commanding a full army and burdened with all of the duties that come with it. If he is to be useful to our cause, then we will need to bargain with him," you explain. A quietude settles between the two of you as Vierna considers the situation, her pride at war with her pragmatism. Could it be that she still hasn't gotten over that one time when you sabotaged her duel with Jezyrene and embarrassed her?

"Then send word ahead of us that we will be having an audience with him," she states. "I will gather my retinue, and we depart before the next hour." Pragmatism is the victor - however much she pretends otherwise, you intuit that Vierna is very aware that House Delyl's present forces cannot defeat an entire fortified trade city unassisted, not even with the advantage of stealth. 'Phase Zero' of your next scheme in motion and advancing on schedule. Mwa ha ha ha ha!

"I will send my familiar out ahead to notify him of our arrival, sister. The journey to his new stronghold is a little under a half tenday if we're mounted, and I do believe that he will be receptive to our visit if we make the right offer."