Weddingbee boards

I have three bridesmaids and have been trying to work with them on choosing their dresses.  My only request is that the dress be in the royal blue family, and I would prefer the same brand in order to get a close color match, but other than that, the choice is theirs.  My plan was to get their picks relatively soon so I can price shop, find the best deal possible, and then order them after the holidays.  Plus I have a bridesmaid in North Carolina (I am in the SF Bay Area along with my other 2 BM) and she's super busy with 3 kids and school, so I wanted to give her plenty of time for alterations. 

Two of them, including my NC bridesmaid, have been really responsive.  They've both researched styles, sent me links to the ones they like (they thankfully have very similar tastes), and the Bay Area BM went bridesmaid dress shopping with me last week.  My third bridesmaid has been completely MIA.  I invited her to go with us to try on dresses and didn't get any response.  I called her after the trip and she said she had gotten my email but hadn't read it all the way through, so she didn't know about the shopping trip.  She promised she would look at the dresses the other two liked and that she would also look for other dresses she likes.  She said she'd get back to me this past weekend but hasn't.  Meanwhile, my other two have each picked a dress that they would like to wear (they are not the same style, but they are extremely similar), and my North Carolina BM wants to order hers immediately because her husband is being deployed in late spring and she is worried that she just won't have the time for alterations after he leaves (the closest place for alterations is nearly an hour away--she lives right outside of a military base in what she says is the middle of nowhere).  My responsive Bay Area BM would also prefer to order sooner rather than later. 

I've been able to work out a deal for everyone, including myself--if I order my dress and their dresses at the same time through the same company, we all get significantly discounted rates.  All three BM are aware of the potential savings of ordering early.  My 3rd BM doesn't know the exact amount since she hasn't picked a dress yet, but the other two know how much each would save (the dresses are different in price).  My two responsive bridesmaids want to save money.  Although she hasn't said so, I know that the third BM would be very much assisted with any savings.  In order to stay within my budget, I have to have this discounted rate for my dress.  None of us needs the third BM to order with us to get our personal discounts, so we don't technically need to wait for her.

I'm not sure what to do.  Should I just tell my third BM that she needs to pick one of the two that the other girls selected, wait on her to decide and just order them in two groups with the 3rd BM paying more, decide for her, or something else?  If I wait, how long should I wait before pushing harder for a decision?  I know I need to order my dress really soon and I don't want the other ladies to lose out on savings, but my third BM might feel hurt or left out if we all ordered without her.  An additional detail is that I don't think my unresponsive BM will like either of the dresses the other two picked.

Advice, please!

Thanks for the advice!

I did send her an email with a deadline of the end of this week, telling her I understood how busy she was but that the others wanted to order their dresses this week and so we were going to place the order with or without her.  I told her there was no need for her to rush on choosing dress A or B, but the others wanted a bigger discount--no pressure on her to do the same but an invitation to join in if she wanted and a list of stores in her area that carried the dresses.

Lo and behold, I got a phone call, I kid you not, within five minutes!  She went to a store last night, tried on the dresses, and picked one.  Guess she got more motivated when she realized I wasn't going to wait on her or that she had a deadline?  :-)