Britney Spears hasn't seen her kids in well over a year, a timeline that could grow even longer ... because TMZ has learned Kevin Federline won't force his boys to see their mom before taking off to Hawaii.
Sources with direct knowledge tell TMZ ... Britney and Kevin's boys -- Sean Preston and Jayden -- will make their own decisions on whether they'll say their goodbyes to their mom before the move in August. Our sources say the boys haven't yet decided what they'll do.
As for Kevin, we're told he is encouraging his boys to see Britney ... but he isn't going to make the decision for them, and won't force them to visit Brit if they're not up for it.
TMZ broke the story, Kevin's attorney Mark Vincent Kaplan sent a letter to Britney's lawyer, Mathew Rosengart, in May -- asking if she'd be willing to let the boys relocate to Hawaii with Kevin and his wife, Victoria Prince.
Kevin needed Britney's approval to take them off the mainland and even put a deadline on the response. Rosengart answered with a few days to spare, confirming Britney wouldn't fight the relocation ... giving them the green light for the move.
Britney posted about her sons on social media after approving the Hawaii trip -- calling Sean Preston her "first love," and sharing a throwback pic of her carrying a then 4-year-old Jayden ... possibly sending an olive branch before they take off.