I'm with John, I think it should be spouse/partner/SO. If we go down the route of immediate family member, then I agree with J. Brewer, it can get a little out of hand.
Arguably, both of these positions will likely be filled by a racer's wife or girlfriend (not always, but most likely). So if we say family member, then a partner or significant other would be excluded because they are not married?
Otherwise, I would suggest a modification to Brewer's rule change addition to section 11 that the secretary and treasurer change from non-racing to racing positions if it gets changed to "immediate family member."