Weddingbee boards

Dilemmas Dilemmas....  I've read stories on here about people who will have BMs that are a few months pregnant, I however, have one that will be further along than that..  I only have a MOH and one BM.  They have both bought their dresses and shoes, and I have bought gifts already (matching purses).  My wedding isnt until March 3, 2012, and I found out yesterday that my BM is 5 weeks pregnant.  Which means - she will be approximately 36 / 37 weeks when my wedding rolls around. 

Sigh...  She's already mentioned having a friend of ours fill in, and wear the dress, however, I really want her   ...  I dont know if I'm whining to just vent or to figure out if I should have a fill in and plan ahead.  I'm really disappointed because we started to plan our honeymoon with her and her husband coming with us just yesterday morning, now that will change as well.  I have a sister that will be home and would gladly take her place, but I will have to buy her dress as my friend's dress won't fit and her financial means are not to the point that she could buy it herself...

Any other people dealing with this or have any words of advice from experience?

I talked to her about it some yesterday and her dress is a jersey knit and she would need alterations at the size that it is right now.  So I think the dress would be okay honestly, and I bought an extra pair of flip flops to take to the beach with me for our beachside ceremony, and I could go ahead and let her wear them if she decides to be in our wedding.  I guess I need to decide if I want the other friend to go ahead and fill in or if I want to just buy my sister a dress. 

What do you all think I should do about the dress? I think she has time to return it if she wants - she just got it in a few weeks ago. 

@AmeliaBedelia:  It could happen to you! LOL  I didnt think it would to me, but I'm not too surprised, just disappointed.  We've done bachelorette parties for other close friends and she got married quickly after finding out her husband was sick so she didnt get to have one, and was looking forward to enjoying mine :(  We're keeping our wedding party down to a minimum - my son and his son are going to be the only ones in it besides my girls.