How to link multiple records on relate to field selection

I have one requirement i.e. I should be select multiple records from custom relate to field. 

Default behavior of relate to field: i can select only one record of related module.

I have make changes to relate.js file. When my condition is met change drawer layout. I have shown multi-selection-list-link except selection-list.

But Now i have to change button from header pane and as well as display multiple records with hyperlink.

Anyone can have solution or idea for doing this.

custom/modules/Leads/clients/base/fields/relate/relate.js

({
extendsFrom: 'RelateField', initialize: function(options) { this._super('initialize', [options]);

},
openSelectDrawer: function() {

if(this.getSearchModule() === "Accounts" && this.context.get('module') === "Leads" && this.fieldDefs.labelValue === "RelateAccounts" && this.fieldDefs.name === "relateaccounts_c") 

   var layout = 'multi-selection-list-link';

else var layout = 'selection-list';

   var context = {

         module: this.getSearchModule(),
         fields: this.getSearchFields(),
         filterOptions: this.getFilterOptions()
   };
if (!!this.def.isMultiSelect) {
   layout = 'multi-selection-list';
   _.extend(context, {
   preselectedModelIds: _.clone(this.model.get(this.def.id_name)),
   maxSelectedRecords: this._maxSelectedRecords,
   isMultiSelect: true
   });
}

app.drawer.open({
   layout: layout,
   context: context
   }, _.bind(this.setValue, this));
},
})

  • How can i change button?
  • How can i save records to the database?
  • how can i set multi selection layout to the drawer except above way.

Here is my record view and relate field

Here is drawer layout view

To Show Add button except create button: 

I have set isMultiLink equal to true within my condition:

///Modified condition

if(this.getSearchModule() === "Accounts" && this.context.get('module') === "Leads" && this.fieldDefs.labelValue === "RelateAccounts" && this.fieldDefs.name === "relateaccounts_c"){
   var layout = 'multi-selection-list-link'; 
   this.def.isMultiLink= true;
}else var layout = 'selection-list';

And set more fields to context i.e.

var context = {
   module: this.getSearchModule(),
   fields: this.getSearchFields(),
   recParentModel: this.context.get('module'),

   recLink: 'account_id_c',
   recContext: this.context,
   recView: this.view,
   filterOptions: this.getFilterOptions()
};

Now button is displayed. But no action performed.

Latest drawer image: