Automatically add template on already existing host

[Prost]

Hello,

For beginning, my configuration :
Zabbix Server : 3.4
OS Zabbix Server : Debian 9.1
I don't know if you need more information for my issue.

I have a lot of monitored servers, and I would like to know if it's possible to automatically add template on already existing hosts if zabbix automatically detect installed package ?
For example, I have servers with apache2 installed and already monitored, and if zabbix detect apache2 installed, it automatically adds template on these hosts.
I tested with auto-registration, but that is only for new host.
I tested too Configuration > Actions > Event source : Discovery (on one IP for beginning), but I think it's the same thing for auto-registration

Do you know if it's possible to do what I want to do ?
If it's possible, how can I do ?

Thanks.

[highpeak]

Did you ever find a solution to this? We add servers via the API but based on tags or other properties like what services are discovered, we wish to add a template to that host. Sounds like we have the same problem.