Create the field called “Contact Relationship” checkbox on the Contact Object and Create the related object called “Contact Relationship” related list to the Contacts.(Look Up Relationship).Now logic is when we create contact by checking Contact Relationship checkbox, then Contact Relationship will be created automatically for that contact.

trigger CreateCRonContactCreation on Contact (after insert,after update) {

if(trigger.isAfter)

{

if(trigger.isInsert)

{

ContactMasterHandler ConIns = New ContactMasterHandler();

ConIns.createContactRelationshipByContact(trigger.New);

}

}

}

Public Class ContactMasterHandler {

public void createContactRelationshipByContact(list List_Contacts)

{

list ConList= new list();

for(Contact newconts:List_Contacts)

{

if(newconts.Contact_Relationship__c== true)

{

Contact_Relationship__c CR = new Contact_Relationship__c();

CR.Name=newconts.Last Name;

CR.Contact__c= newconts.id;

ConList.add(CR);

}

}

insert ConList;

}