If two Vamps try for baby as bats, the child will automatically get the bat form power upon becoming a teen (you can put those 2 points towards something else). This is always the first one I choose because it makes it so much quicker to get out of the sun after school or work.
As has been noted, carefree cancels guilty drinker so that's a great one to go for. I also choose withered stomach because food does nothing for them.
I don't worry about the age "difference" between the parents and kids because aging stops at YA for Vamps born in game and teens/YAs/adults all look so similar anyway that it just doesn't matter to me. :D