I know i am over reacting but just need a vent...

Slightly annoying but then she is allowed to buy an outfit without your permission.

I don't think you can compalin, as long as they don't wear the same thing! 

Yes you are over reacting.  Your MIL should be allowed to wear whatever she likes and is comfortable in for your wedding

I don't see the problem. Even going to the same shop it is doubtful they would pick the same outfit. My Mum & MIL chose their outfits without my input. They are grown woman after all.

Its Tradition that MOB chose her outfit first.

Thats what we are doing, my mum has chosen her outfit and colour and now MIL2B is choosing hers.

I would not let it bother you my MIL went shopping and so did my mum ended up both with light grey without the other one knowing and I think both there outfits are lovely (and I dont really get on with MIL lol)

Lx

I think you are over reacting.

Surely she has the choice to wear what she wants and the day is important for her too.

I don't think it is fair to demand that the Mother of the Groom wait until the MOB has got her outfit and then tell her to work around that colour, especially when she is paying for her outfit.

Although it may be an old tradition for the MOB to choose first surely all you can is request that she waits and if she does not then so be it. 

My bridesmaids wore midnight blue, my mum wore a very pale pink and my MIL wore duck egg blue. They both had beautiful dresses and jackets and both felt comfortabe in what they had one. They did not match 100% but they are not standing together on the posed photographs anyway and both looked lovely next to the bridesmaids.