the easiest way to express it is probably in the kotlin code - but you might end up doing more copies than you want if you are changing more than one value

data class Thing (val thing1: String, val thing2: String) {
   fun copyWithThing1Change(_thing1: String) = copy(thing1 = _thing1)
   fun copyWithThing2Change(_thing2: String) = copy(thing2 = _thing2)
}