Weddingbee boards

I've already got a great MOH and one other BM who are enthusiastic about the roles, but my question is this:

How long is it polite to wait for a yes/no answer about being IN the wedding party or not, before 'replacing' them?

I've tried my best to address time and cost issues; if she's too busy or can't afford it, that it is understood.

Unfortunately, she can be a little aloof and hard to get in touch with. Email, facebook, phone etc you name it she's either not around or can't talk at the time.

Biggest thing, I don't want to offend her or cause any unnecessary drama between the girls & myself.

I would try to get in touch with her and have a heart-to-heart.  Explain to her that you completely understand if it is not something she wants to or can do for whatever reason.  Be sure to let her know that you need to know in a day or two, as you are trying to finalize details.  If she doesn't give you an answer or disappears again, my best advice is to let her know that you had to make a decision and had to ask someone else.

Unfortunately, it seems there will always be hurt feelings over choosing BMs.  You want to make sure that you and your FI are choosing people who you really want to support your marriage to each other and that you plan on them being in your lives for years to come.