Tracking Multiple Domains & Sub-Domains in Google Analytics in one Profile
Many websites use third-party resources for availability calendars, to process payments, etc. This is actually a fairly common need. The good third-party applications allow the ability to insert tracking code.
This can be for affiliate networks or standard website tracking to evaluate performance. Google Analytics is one of the most popular website statistical tracking implementations.
If you need to track a main domain, a sub-domain and even a completely different domain under the same profile, it can be done.
Google spells it out for you, but a developer will need to make the implementation: