I am not sure what the charity is that you are quilting for, my church has done quilting for Lutheran World Relief (LWR). LWR has criteria for the size and weight of the quilt along with other criteria. The quilts may be used for people, but it is more likely that they will be used for animal covers, ground cover or shelter. That is part of the reason that so many different types of fabrics may be used, most of which are recycled (still clean and usable however). My church is moving away from donating quilts to LWR because, LWR wants a monetary fee with each quilt for shipping and no religous symbols can be used and the rules keep getting harder to follow.
I would also ask questions to the quilting group so you have a better understanding. "This is how we have always done it" is not an answer.