I'm not entirely sure how the pantheons hierarchy works but I think that the Father is in charge similar to Zeus's position in the Olympian Pantheon. So I'm thinking that's the Seven or at least the Father expected their Chosen to mimic said heriarchry therefore they only gave Lucan the vision and he'd direct the other Chosen on combating Viserys. Though your theory is also valid.
I believe a significant part of their issue may be that they have spent the last several millennia backing themselves into a metaphorical corner. Too much time, and too much faith from devout worshipers, have shaped the Seven in unfortunate ways...for them. Magic is anathema, the Seven Champions are all they need, the Others are insignificant threats, if they even exist, etc.
They lied too much, and now they're stuck trying to uphold an impossibility. Seems legit.
That would work if all their chosen were near each other, but they were choosing champions all over Westeros, sure some of their chosen have met each other at this point, but for all we know, it might be that Danella and Lucan meeting each other, is it for them meeting each other, Brienne probably haven't met Lucan, and we don't know anything about the chosen of the Mother the Smith, the Crone,(aside from the Crones first chosen being dead, but she has probably picked a new one) and the Stranger, so it's far from sure they have met Lucan.
Danelle is the Chosen of the Maiden not the Mother, we have no idea who the Chosen of the Mother is.
Divination is on Danielle's spell list. I expect her to make extensive use of it during her negotiations with bloodraven.
Yeah the negotiations will be interesting, but in the end peace is unlikely, as the Seven wont want to pay reparations to the old gods, and the old gods, aren't going to let their ancient crimes stay unpunished.
Viserys is more effective at the negotiating table than the battlefield.
Seeing as that would decrease how many fucking irons we have in our fires, and possibly let us point Danelle and her group at more pressing targets...
While begging from Danielle is very much in the table (she's cares for people and is not proud so she'd probably do it), actual concessions would have to be run past The Father, who's clearly not in the mood for negotiating if the attempt to sick Baelor on us is to be taken seriously.
The Maiden trusts Danielle. How much the others poke their heads into what the Maiden does with her Chosen is part of the question on how tied together the Seven are.
