if sold at a loss nothing to report this is personal loss
if a gain each of the 8 would have to report their proportionate part of the sale of form 8949. even thogh mom apparently gave her share to sibs she has to her share of the gain. mom made a gift of her share of proceeds to her sibs. if the amount gift to any sib was over $15,000 a gift tax return for 2019 is required.