Azure collection

i have a question maybe someone can help me in relation to collection azure.azcollection.
when running the modules
azure_rm_virtualnetwork
azure_rm_subnet
when deploying a VM as part of a playbook the 2 about need to be created first within a RG.
but if I want to use an existing subnet and vNET you just add the existing names of the vNet & subnet correct?
as the vNet will already have a subnet associated with it as its an existing Vnet I don't need to run the task for azure_rm_subnet correct?
an help would be appricated

• name: Create a Virtual Network
  azure_rm_virtualnetwork:
  resource_group: "test-ansible"
  name: "exsisting Vnet"
  register: vnet

thanks
Shane