Corsages for my sisters?

I have 2 sisters who are 15 and 11 years older than me (same parents). Our mom died when I was 9 and they helped take care of me after she died. They are not in my BP, but I'm having them do a reading. Do I get them corsages? MOG and my step mom are getting them (my dad remarried when I was 12 and my step mom is a huge part of my life). My WP says I don't have to, but I feel I should do something to acknowledge them as important women in my life who helped raise me, and I thought giving them a corsage would be a nice way to do that on my wedding day. Should I go for it despite my WP's thoughts? Is it weird to give corsages to female family not parents or grandparents (we have no living grandparents, so that's not a factor for us, but I know people do it for grandmas). Is this a situation where I can just do what I want?