How thoughtless of the other bridesmaids not to take a vow of celibacy during the year plus of planning for the wedding. Now that they have been so derelict in their duties, they must consider how to make amends. The one who will have the baby at the time of the wedding should consider giving it up for adoption so she won't be distracted by having to nurse the child. The seven-and-a-half months pregnant bridesmaid should have a premature, induced delivery. This will allow her to wear a regular bridesmaid's dress and leave the infant behind in the ICU. As for you, why don't you just give your friend your bank account PIN so she can access your funds without having to bother you with specific requests for money. Alternatively, the three of you could get together, agree to have one of you act as a spokesmaid, and explain to the bride that she's planning a wedding day, not D-Day. Unless she is able to get a grip on her obstetric and financial demands, all of you will have to decline the honor of serving as her attendants.
Read the letter she's responding to here.