CATHOLIC CHRISTENING ADVICE NEEDED PLEASE?

Hi there having my 4 children christened in august 2 boys 2 girls girls ages 12 months and 6 and the boys 4 and 3 i was thinking of putting the boys in kilts to wear as they are to old for gowns and the girls in lovely white/ivory dresses just wonderd if this was ok or do they have to be in gowns any help would be great thanks.