So our situation is a little different because we don't live together, but Dee and I can kind of relate because our guardians are dating and at this rate probably will be living together one day soon. It CAN get a little awkward but I think your brother and Clint love you guys enough to support you if you guys want to give it a try.
And I don't think your siblings would have a problem with you dating at 16. You MIGHT want to talk to Klaus and Clint just because of the weird position you're in, but you probably don't need actual permission.