>>15688220It definitely works, I got a perfect egg earlier but it was the wrong gender, since the gender is set aswell. You might not be saving/resetting to the right point. You save -before- the egg is generated, so right after rejecting an egg. Then if the egg isn't what you want, you reset, run around until the egg is generated again, reject it, save, and try again. You can use dittos.
>>15688301Resetting and swapping the parents does not reset the random IV or the deciding which IVs the destiny knot will pass down. Assuming you're saved in the right place you're free to swap the parents for whatever and it will pass down the same IVs except from the new parents, and the non-inherited IV will be the same.
>>15688377You can swap both, or just one, doesn't matter, so long as you can figure out where the child is getting the IVs from (for example Atk and Def from the mother, HP, Sp.Atk and Speed from the father with Sp.Def being non-inherited) and then reset and put in parents with the right IVs (a father with 31 Atk and Def and a mother with 31 HP, Sp.Atk and Speed).
It's kind of hard to explain with words, but it definitely works.