Many thanks for the feedback! Indeed, when one of the adult jims takes care of the baby, the benefit of the interactions goes completely for the little one. Meanwhile, that adult can't do anything "productive". There is one exception, though: putting the baby in the cradle frees the adult, who then can take care of its own necessities.
PD: Just for the record, none of the jims has been severely hurt during the jam---they are from a tough species. Although family comfort surely impacts productivity.