i used a christening robe which my grandmother and her mother were christened in, i wore it and my two boys have worn it. it was really delicate so needless to say it was only kept on for church. it was lovely. my gran had 13 children and each one of them wore it too. not sure exactly how old it is but its over 100 years.
as for the first communion, my plan was to get my wedding dress made into communion dress but i didnt have any girls, so dress stays intact in the attic.