. Now I know we're having another girl, I buy more readily for DD because I know it'll go to DD2.

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Ooh be careful with that. I found many of DD1's clothes have not passed on to DD2. She either won't wear that style (she is such a skirt girl), or it just plain does not suit her. You would not think it, but the girls have slightly different colouring. DD1 could carry some more unusual colours so well, that look awful on DD2. I am now cutting back with DD1's clothes. The only stuff I buy thinking about DD2 wearing it in the future are school uniforms and warm jackets.