Custom Service Application on Application Server creating Sub Sites

Hello,

I am working on  Custom Service Application .

So now my Farm is as follows –

1 Web Front End
1 Application Server
1 Database Server

Services enabled on Web Front End –
1. Central Administration
2. Microsoft SharePoint Foundation Incoming E-Mail
3. Microsoft SharePoint Foundation Web Application
4. Microsoft SharePoint Foundation Workflow Timer Service

Services enabled on Application Server –
1. All Service Application
2. My Custom Service Application

Now, I have Custom Solutions (wsp) which gets deployed at Web Application Level and Custom Service Solution (wsp) gets deployed at Farm Level. in one of my solution (wsp) I have custom web templates, Master Pages, Page Layouts and that solution gets deployed at Web Application Level

In my Custom Service Application which gets executed on Application Server I have a logic which creates Sub Site. But while creating Sub Site it says Web Template not available and this is because Microsoft SharePoint Foundation Web Application Service is not enabled on Application Server. If I execute same code via PowerShell on WFE machine it works.

Could you guide me in a manner that, My Custom Service Application on my Application Server will create Sub Site using custom Web Template.

Thanks in advance.

Regards,
Piyush