I think the only time I use language that indicates one of the two for sure is true is with Luke: “Because you’re a Palpatine? The Force alone made us, to end him.” I can simply remove the word “alone” to allow both interpretations to still stand - “The Force made us, to end him.” That sentence could be true even if Palpatine had a hand in their creation, because as we later know he wants Rey to kill him. That being said, I think for a satisfying conclusion most of the evidence should point to Palpatine lying and stretching the truth. But in terms of it being outright stated which version of events is true, you either have to believe space Satan or a ghost of a dude that really shouldn’t know one way or the other because he wasn’t around for these events.

I’ve also figured out a way to make it clear that what Kylo is telling her may be unreliable:

“Palpatine told me the rest of our story.”

“Tell me.”

"He influenced the Force itself into creating life. First my grandfather, and then you. You were his chosen heir. You… are a rightful Palpatine.”

"The Emperor only wants us to fight each other, so his most worthy heir can claim the throne. But he hasn’t realized the strength of our connection, Rey… a bond, not of blood, but of raw power in the Force. We can end him and the Sith, and create a new order, together…”

I’ve also found a way to keep Rey’s parents fearing her for her strange existence and possibly her unexplainable dark power:

“I’d never lie to you. Your parents were no one. Junk traders expecting a child they never wanted.”

“Don’t!”

“They feared your nature. Your conception had no father’s hand.”

“I don’t want this!”

“…just like Vader.”