How do I add system-generated contacts to a contact group

Is your feature request related to a problem? Please describe.

contacts doesn't support adding system-generated contacts, and I tried to add system-generated contacts to a contact group by modifying the code, but that didn't work.

addContactsToGroup(group) {
			console.debug('Contacts picker opened for group', group)

			// Get the full group if we provided the group name only
			if (typeof group === 'string') {
				group = this.groups.find(a => a.name === group)
				if (!group) {
					console.error('Cannot add contact to an undefined group', group)
					return
				}
			}

			// Init data set
			this.pickerData = this.sortedContacts
				.map(({ key }) => {
					const contact = this.contacts[key]
					return {
						id: contact.key,
						label: contact.displayName,
						type: 'contact',
						readOnly: contact.addressbook.readOnly,
						groups: contact.groups,
					}
				})
				// No read only contacts
				// .filter(contact => !contact.readOnly)  comment this!
				// No contacts already present in group
				.filter(contact => contact.groups.indexOf(group.name) === -1)

			this.showPicker = true
			this.pickerforGroup = group
		},

Describe the solution you'd like

I want contact groups to support the addition of system-generated contacts.

Describe alternatives you've considered

I don't know exactly how to implement it at the moment, and if anyone can give me some advice, I would be very grateful.

Additional context

Start by locating the addContactsToGroup(group) entry point shown in the issue and trace how pickerData and group membership are handled for system-generated contacts. Compare the current readOnly filtering and group assignment flow with the contact data shown by the picker. Done means system-generated contacts can be added to a contact group without breaking existing read-only behavior.