Most bridesmaids can order their dress in the right size, so it needs fewer alterations, but when the dress is discontinued or on clearance, the correct size may not be available. In that case, it is usually better to buy a dress that is too big, rather than one that is too small.
A bridesmaid dress can easily be taken in 2 sizes but taking in more than 3 sizes may require costly recutting and redesign to make it work. Reducing a dress by several sizes makes it difficult to keep specific details of the gown.
A dress that is too small can be altered to be bigger, but it is a bit more challenging to have the alterations blend in. To let out a dress by one or two sizes involves releasing the side seams or adding a gusset for more room. Adding a corset back can increase the bodice width by up to 5 inches if needed.