I've looked endlessly and haven't come to any conclusion about this, but would the victors' children in a district (if they had one or a few) be equal candidates for Reapings?
Yes. And there's a suspicion that it may even be MORE than equal. This is discussed and affirmed as a fact in Book 2, "Catching Fire", Chapter 4:
I wonder if President Snow will insist we have children. If we do, they'll have to face the reaping each year.
And wouldn't it be something to see the child of not one but two victors chosen for the arena? Victors' children have been in the ring before. It always causes a lot of excitement and generates talk about how the odds are not in that family's favor. But it happens too frequently to just be about odds. Gale's convinced the Capitol does it on purpose, rigs the drawings to add extra drama. Given all the trouble I've caused, I've probably guaranteed any child of mine a spot in the Games.
She says similar, if less informative, thing in Book 1:
... I know I’ll never marry, never risk bringing a child into the world. Because if there’s one thing being a victor doesn’t guarantee, it’s your children’s safety. My kids’ names would go right into the reaping balls with everyone else’s....