Given that campaign 4 is an actual play show, first and foremost, my belief is that any character related to the PCs whose fate is up in the air (i.e., Julien's mom and sister, Alogar) is currently still alive and will remain so until the Seekers find them. I'd even reckon that one of the Royce cousins made it, though that may be pushing it.
My reasoning is that it would be both a betrayal of player agency, especially with Brennan's more structured plot given that he's the one setting the pace a lot. The Seekers have their goals (get to the Golden Orchard, reunite with what family still remain), and its pretty obvious that by the end of the arc, we will have established the fate of at least one missing family member.
Like with the search for Cyd for the Soldiers, I think that the players would have to go WAY off book to create a scenario where he would make the death of a family member a consequence. For example, I believed him when he said there was no wrong choice for where they went to go get Cyd de-statued, nor did I think he would punish them for not finding Cyd at the inn. Cyd did end up in a bad situation, being petrified, but he absolutely can be saved, and even if the horse cart had made it out of the castle, I believe he would have given the Soldiers a fair chance at stopping it before it reached the gates.
I mean, I think all these characters might be in danger, like once the Seekers find them, they most certainly will have to rescue them in some way, and Brennan will likely not make it easy, and if the whims of the dice are unlucky, they may not make it, but it makes way more sense for them to be alive to rescue than dying off screen without the chance for character intervention.
