Yes, fill the VFS webform - https://vfs-cic.mioot.com/forms/PS/That's great, I hope your parents get their visa's soon!!
On the webform on VFS website where you request passport pick-up, what is this question about?
Did you enrol Biometrics for this application?
Do you answer Yes if BM were already done in the past?
I selected Yes for BM.