If they have true love they can't have sex for procreation.  It's an explicit contradiction. For a male it would be like making love to a toaster. What Butcher writes but doesn't state explicitly is for the human to have the protection the human must be monogamous to the person loved.  But if they are monogamous the human is like a hot element in a toaster, but if that isn't true, then they don't have true love. In practical terms you have a couple where the women is monogamous and the man is running around.  A White could eat the husband but not the wife.  I don't write this stuff I just try to understand what Butcher is selling.

First, no vampire child could have ever been a product of true love.  Think about it.

Second question I get that the Big Foot's boy can feed his vampire lover because of his reserves but how does she keep from getting burned if they have true love between them?

• Irwin is a half-human scion, hence his huge reserves. It is possible his (partial) non-human nature annuls or mitigates Connie's true love allergy
• Connie never killed during her first feeding. Usually to complete their transition, a Whamp's first feeding must be fatal. But Irwin never died. So it is possible that Connie's Hunger isn't 'fully developed' and is thus less vulnerable to true love.
• Connie and Irwin appeared to be in love before their first sexual encounter. Usually that would kill the Hunger. But again, the act was never completed. It's possible this partial experience with true love 'inoculated' Connie's demon, so to speak, making it more immune to true love.