Merging zoho components?

We set up a free Zoho invoice module about a year ago and added the free website module not long afterwards. Since this worked out so nicely for our purpose, we decided to set up a Zoho account using our own domain name so we could add email and ultimately port our whole website to Zoho, whose features are more advanced for a better price. The older account's primary email was with a common email provider, but not with gmail.

We cannot change either the primary email address in the old account to the new one or add the new one (with our own domain) as a secondary because Zoho's system states "address already exists" (yes of course the other address exists). Is there a way to merge the older account into the new one? Having added a couple of hundred invoice items to the invoice module, we'd like to avoid having to add everything over again - even though this can be done by importing data (such imports are rarely if ever without flaws).