Adding more than one virtual machine to an existing Vapp

Hi

I have created a  Vapp ovf and deployed it to create 4 VMs.

I want to add 2 more VMs to this Vapp using a new ovf (single ovf should deploy 2 machines).

If I create  a new Vapp ovf (containing new VMs),it creates  a new Vapp and doesn't create VMs in existing Vapp.

If I do not include Vapp in my ovf, it deploys one machine only to the existing Vapp.

I do not want to create machines and drag drop them to intended Vapp.

Could somebody please suggest a way to do this?

I am using Venter VCSA 6,ESXI 6.0