Siblings in the wedding??

Hey y’all! So I have four siblings, two brothers two sisters. Different parents. So my fiancé and I are sponsoring our own wedding with little help from other parents just in case someone asks. My brothers are good on everything. Neither of my sisters have purchased their dresses and after the second deadline I just sent their (our) moms the link to purchase the dress on their own. Two weeks have gone by and they’re still not purchased. I’d gotten to a point I didn’t care when they got here as long as everything else was in order but now I’m at the point where I feel I’ll be saving money and time and stress by just not including them. I won’t have to pay for their makeup, accessories, gifts, etc. No I’m not super close to either of them but we’re not enemies either. Should I just tell them not to worry about it and just walk down the aisle with the rest of the family or still include them? They haven’t done much with anything and I get they have other things to focus on and this isn’t a priority which is why I want to take the responsibility off of them so it doesn’t stress me out when I have expectations from my sisters and they don’t meet those expectations. Again, both of my brothers are taken care of so they’ll still be in the wedding. What should I do or consider? Still let my sisters be in it or ask them to walk with the family?