Should i invite my bil and future bil to my bachelor party?

I'm planning a surf trip bachelor party with my buddies from high school which includes my best man (7 guys total). For background, my fiance and I are only doing one best man and one maid of honor, no other groomsmen or bridesmaids. Honestly, the trip was first planned to be a surf trip and then happened to evolve and serve as my bachelor party. I asked my fiance if she cared that I invite her brother (my future BIL) to the trip. He doesn't surf and she didn't care, so I didn't. There is no drama between my fiance, me, or her brother about this trip. He's an easy going guy and great to get a long with. But I'm now getting grief from my own sister who is offended that I didn't invite her husband (my current BIL) on the trip. He invited me on his bachelor party when they got married but I feel it is different because he was marrying my sister and my sister wanted me to go. We've also somewhat butted heads in the past but nothing serious, we get along fine. It's honestly causing me a lot of stress and anxiety now, the trip is in 2 months and my sister is saying she's hurt about it. I honestly don't care if they come or not, I didn't invite them because it's a specific kind of activity trip and not a general drinking stag party, it wasn't as if I specifically excluded him when I planned it, I just didn't think to invite him. I feel if I invite one, I should invite both my future and current BIL. Is it too late to extend the invite or is it now already seen as rude on my part that the trip is already planned and they are an "after-thought"?