I feel your pain! I didn't get a cold sore until I was 31! I got it from my 12month old son, who got it from my mother-in-law. I did a lot of online research to find ways to treat them, without taking the oral medication, to make sure it was safe for my son. Here is what works for me:
I use L-Lysine and vitamin C. I take the supplements daily, but you could probably take them if you know one is on the way, or at the first sign. I've used this for the past three years and have only gotten an outbreak when I've forgotten to take the supplements for a few days before a time that causes them, i.e. a bad cold or around my monthly.
Use ice when the outbreak is starting. This will reduce the swelling, and can shorten its lifespan. I use ice for hours on end, as long as I can feel the 'fever' on my lip. For topical I use vitamin E, a chapstick with Neem Oil or a homeopathic lotion by Peaceful Mountain called Cold Sore Rescue. The latter has a bit of an orange color to it, which will look kind of strange as it dries, and has a nice herbal scent. Lemon balm and vitamin C is especially helpful for cold sores. The E, and chapsticks help keep the sore from splitting open and taking longer to heal.
As far as someone else in your family getting cold sores, keep in mind she's pretty much always contagious on some level, just more so during an outbreak. Some people have better immunity to the virus than others. I'd keep the children from sharing eating and drinking utensils & encourage cheek kissing. The good thing is that as you age, the frequency gets less. Good luck!
P.S. If you're worried about the size of the L-Lysine pills (and they are BIG) grind one up with a mortar and give a portion of it to her in her food.