Sister Can't Attend Wedding - Reschedule??

So I am planning on getting married on August 11, (in 6 months). I've been making the rounds and telling all family the date, but when I told my sister, she said that she would be at BOLC the whole summer until the end of August. For those that don't know, BOLC is an 16 week Army training that is basically impossible to take time off from. So, I can basically count on her not being able to make Aug 11 (there is a tiny chance, but not realistically). I was planning on having her be one of my only TWO bridesmaids, the other being my best friend. We're very close, and I was a bridesmaid in her wedding also. I'd feel horrible if she couldn't make it. Conversely, the summer is the only time we can get married this year due to college schedules. The only option to keep my sister in the wedding would be to postpone the wedding to NEXT summer. Obviously, I don't want to do that. I hope I don't sound selfish or anything, but I really want to marry my fiance soon, and would be upset if I had to postpone a year. But my dad and step-mom strongly encouraged me to either postpone or have a elopement so she wouldn't feel left out. Advice?? What would you guys do??

RE:Sister Can't Attend Wedding - Reschedule??

I'm guessing you're not that close to her because you booked before even confirming with her if she could make the date? And you weren't aware that she was even doing this? If she wasn't a priority when setting the date, then I'd say to get married this summer and nope she's able to make it, not necessarily as a bridesmaid. If you were to postpone, I'd say wait until the fall, which I think as college students you can surely take a weekend to do so, no? Life happens when planning a wedding and there will always be something. If you're not willing to wait a year for your sister, hopefully she understands that your life must move on.

RE:Sister Can't Attend Wedding - Reschedule??

If you were close wouldn’t you have known she had this program before you booked the date? First mistake. 

RE:Sister Can't Attend Wedding - Reschedule??

I agree with them, but I'm certain that your sister will understand your situation.