Well In my opinion you should go ahead and invite them. I understand that you want a small ceremony but it'll still be small especially if your sisters might not go. You are obviously close to them as you have shared your plans with them and I believe you said previously that you haven't announced your engagement. FI must share a bond with them as well since he initially wanted to invite them. As for the other aunt and family uou aren't close to them so they shouldn't really feel any type of way about it. And if they do oh well it's your wedding and your wishes and that they should understand. .