I do something similar, although I download updates manually when I am made aware they exist and I think they are necessary and save them to a local repository (network drive shared wtihin my VMs). I then run them inside the VMs. The main reason for me to do it this way is that our company policy prohibits the VMs themselves from accessing the internet.
My understanding is that the downloads themselves are standalone installers so, at worst, you could just copy and run them in the needed VMs manually.