Can you change Gigarank domain without losing content?

Hi all, thanks in advance for any help. I used the forum search tool, and couldn't find any results for my question.

I have a free hosting account here, and am wondering if it's possible to swap out the main domain associated with my account, without losing any content? I have an add-on domain also on the same account, and don't want to lose that content either.. Basically, I just want to change the main domain for a different project.

Or, if since I have the add-on domain-- if I just create another add-on domain for the domain I plan to use more often, and leave this original/main account domain as it is, will that be ok? I don't want to get in trouble if it looks like it's just a parked domain with no activity really going on.