How do you/can you? freeze live mussels in the shell? There is a lot of conflicting advice.
I’m sure this answer is too late for you this time so I’m hoping you share what you eventually decided to do. From all I managed to read on the subject freezing live mussels in the shell is not highly recommended. It is possible to do but the shelf life is rather limited (approximately 3 months). A better choice would be to steam or boil the mussels to open them. Boiling in brine keeps the meat from shrinking. Remove the meat from the shells then place on a cookie sheet so they don’t touch and freeze them. You can then take the frozen meat off the sheet pan and put it in a vacuum pack and back in the freezer. Or you can can the mussels in a pressure cooker with brine. The most complete discussion of preserving the mussel harvest I found is from the Food and Agriculture Organization here.