Can a dynamic query identify a particular service?

I think it can be tricky, you want to monitor a service before knowing if the service exist.

One way though could be to utilize the information gathered in Asset inventory. There you can see if the application is installed. If so, a group membership can be applied. (might need to add a custom property logic between these steps though).

Thank you, the asset inventory does indeed show the application, so is there a way to update a custom property automatically?

Either you create a script, could be a powershell script, that calls the API to make such change. Or you can create an alert rule that triggers when the application is found but custom property is not set, then an alert action that updates the custom property. Easiest if you don't want to code.

Ok, so I've created a mandatory custom property that will need to say if the application is installed, the group membership then is based on that property, so far so good.  I then created an application monitor template to monitor the service and applied it to the group, however, there are 48 servers in the group but the monitor template only shows 30, are there limitations against application monitor templates?  I see no reason why, the 30 seem to be a random selection, if I test the template against a server not in the list, it tests fine.

If the servers are int the group and the application template is assigned to the group, the template will be assigned to each server - eventually....

Sometimes it takes a bit of time. You wrote this post 22hours ago so it should be ok by now though.

There is no limitation on this usage, I have applied an application template for groups with several hundreds of members.

Unfortunately that wasn't the case, I have unassigned the template and tried again. when I go to assign the template it actually states that there are only 30 Agent & WMI nodes But there are 48 servers in the group as below, any ideas?

But I can only see 24 servers, and then there are 24 hosts. Vmware/HypeV-hosts.

Are they monitored with agent/WMI? Or can there be snmp-monitored devices in there? 

Yeah, the Hyper-V hosts are WMI and the servers are agent monitored, there are no SNMP devices.

Hmm, ok. Then I don't know. Maybe something for support then to have a look at.

Try using AssetTag,

We use them to define what service need monitoring.

eg, IIS, WEB = Monitoring IIS Services (w3svc)

SSLW = Monitor IIS Web SSL Certs (custom Powershell script)

I think you get the meaning.

The create a Group with a dynamic query, Create a template with the services you want to monitor.
using my examples.

Application template to monitor IIS Web Service (W3SVC), then assign the dynamic group to the template.
when a system has asset tags containing the chosen wording. it will auto populate the nodes to monitor and alert on.

Sample Dynamic Query.

IsServer = True
AssetTag Contains "IIS"
AssetTag Contains "WEB"

you can apply more filtering as required.