CompuServe Messages

Is there a way in Metaballs to select only a specified group of balls to assign MSHAPE? I tried hiding the group I did not want to assign, I've also tried to freeze the group, but MSHAPE still assigns a mesh to the group I do not want it to assign. I've found a work around by selecting the group I do want assigned and saving it, then deleting the rest, then bringing the deleted ones back, but this seems like too much extra work, is there an easier way. Thanks.