iis 7 - ssl certificate should be added in more than one web site in IIS 7.0

I have purchased one SSL certificate which should run on domain and subdomain.
E.g. *.example.com.

I want this SSL certificate to run in domain website and subdomain website. I have two different Website in IIS 7.0

1. example.com


2. xyz.example.com

Currently the SSL certificate is assigned to xyz.example.com and it is working very well.

Now I want this certificate to work in example.com website as well. I have added the certificate and it has taken default port for https i.g. 443. Now when I have start the website, it gives me below message:

This Web site cannot be started. Another Web site may be using the same port.

Now, I have changed the default port of https i.g. 443 of example.com to 445. and tried to start the website and it gives me below message:

The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020)

Can you please help me in this.

Thanks in advanced

Pranav