attachObject 
  inline suspend fun CloudDirectoryClient.attachObject(crossinline block: AttachObjectRequest.Builder.() -> Unit): AttachObjectResponse
Attaches an existing object to another object. An object can be accessed in two ways:
- Using the path 
- Using - ObjectIdentifier
Samples
import aws.sdk.kotlin.services.clouddirectory.model.ObjectReference
fun main() { 
   //sampleStart 
   val resp = cloudDirectoryClient.attachObject {
    directoryArn = "arn:aws:clouddirectory:us-west-2:45132example:directory/AYb8AOV81kHNgdj8mAO3dNY"
    parentReference = ObjectReference {
        selector = "$AQGG_ADlfNZBzYHY_JgDt3TWcU7IARvOTeaR09zme1sVsw"
    }
    childReference = ObjectReference {
        selector = "$AQGG_ADlfNZBzYHY_JgDt3TWSvfuEnDqTdmeCuTs6YBNUA"
    }
    linkName = "link2"
} 
   //sampleEnd
}