You will need to create an additional account for another family member. Each member receives their own nutrient goals in their individual account that follow their weight loss goals, as well as basic American Heart Association recommendations for their profile. Sparkpeople meal plans and recommendations are for adults 18 and older.
There are features in place that help family members use the site together. First, there is a substitution option in the meal plans themselves to select other foods than what is showing. Food items available in the substitution feature match the nutrients of the food being replaced. Next, the add a food feature is available if you want to use one member's meal plans and track in the other account with add a food (you might not need to do so with all meals of the day). The add a food feature has favorites and food groupings options to make tracking faster in the future. Manually entered foods, under add a food, can now be shared with all members and is searchable by username to add a family member's or friend's oods. You can also use the www.sparkrecipes.com
site to save family recipes for tracking as well.
Hope that helps!