Any attribute that can hold multiple values, is replaced on mass-updates.

For instance:

• Applications on items
• Flexible intervals on items
• Host groups on hosts

It seems fine for "Link additional templates" on hosts.

The GUI seems to offer no possibility to do the following mass-update:

Original situation:

Item A, Application A
Item B, Application B

Goal:

Item A, Application A, Application Z
Item B, Application B, Application Z

I haven't found out, if it's possible with the API. I don't dare to do it in the database because of the code sitting in the frontend, that handles template inheritance.

Might be related to https://support.zabbix.com/browse/ZBXNEXT-170