Hi. We have a home built in 1915 with 7 fireplaces, and two chimneys. We’ve lived here for 7 years and have never used the fireplaces and have no plans to do so. A mason looked at the exterior of the chimneys and said they were fine, considering their age. They each have proper flashing and a chimney cap. Nevertheless, I’ve noticed that in all of the fireplaces, there is a sand-like substance that falls onto the floor of every firebox that I have to periodically vacuum out (pic attached). Based on my research, I would assume that this means that the flue mortar is disintegrating and that the flues should be reclined? I would also assume that a cast-in-place flue liner—like Golden Flue—is the only fix for this? Further, there was a fire in one of the fireplaces, long before we bought the house, and the firebox clearly needs to be rebuilt. In that fireplace, I have to vacuum up leaves (pic also attached)! Would a cast-in-place liner fix this problem, as well? Finally—thank you for your patience—my understanding is that the cast-in-place is done for each chimney, which then vents into separate fireplaces, which would mean that we would need, if appropriate, two casts? I’ve tried to educate myself before bothering folks on a forum, but I can’t seem to get clear on these issues on my own. Thank you.