Hi Laura – Freezing would only deactivate the mould and not actually kill it. It would start growing again once it returned to room temperature. I suggest a separate box (polyethylene or polypropylene) that can be sealed tightly and place silica gel (along with a datalogger) inside to reduce the moisture content of the dolls. Wrap the dolls with a soft cotton or silk fabric first to provide some padding, protection from light (if the box is not opaque) and provide a means to safely remove the doll from the box. Lowering the moisture content of the dolls will also deactivitate the mould but not kill it. Killing mould spores without also damaging the artifact itself is impossible. But with the dolls enclosed in a sealed box with low moisture content, at least you can keep the dolls at room temperature.
Margaret Geiss-Mooney, Costume/Textile Conservator in Private Practice, Professional Associate – AIC