As of this time, merging two accounts or transferring data entirely is unavailable in QuickBooks Online (QBO). You can, however, transfer data like Chart of Accounts, customer, vendor, and products and services list manually by exporting from the old account, then importing them to the new one.
Can I merge two accounts in one without losing the data transfer my subscription from one to the other
To merge two QBO Online companies, each QBO dataset will need to be converted to a Desktop version of Quickbooks first. The desktop files are merged and will need to be uploaded to a new QBO company file. Can the merged desktop files be re-uploaded back to the QBO account? Yes, the merged desktop file can be uploaded back to the QBO account but if your account is older than than 60 days, you will need to contact Inuit to get permission to upload the merged data back to the original QBO account. If not, you will need to create a new QBO account. PM me if you need any more information.