It seems that you're already thinking clearly about the issue. Draw the line wherever you are comfortable.
If you have a source for the family member, I like to include it in their relative's profile, so someone else who wants to create the profile has access to it. In your example, something like "John's first wife was Jane Smith; b. 1 Nov 1937 in Kalamazoo, IN, d. 15 Mar 1962 in Wayne, IN<ref>Source Citation Here</ref>. Her parents were Fred and Wilma Smith.<ref>Source Citation Here</ref>"
I do this more often for children:
Children:
#Barry, b. 1762, d. 1810, m. Sally Jones<ref>Source Citation</ref>
#Bethany, b. 1763, d. 1805, m. John Collins<ref>Source Citation</ref>
etc.
I recommend trying to include any info for family members that you have sources for.