Are you referring to having it in one subscription? If so, the
feature to merge all your QuickBooks Online (QBO) account in one subscription
is still unavailable. One QBO is equivalent to one business.
What we currently have is
the ability to use one email address for all your account and
easily switch between companies any time by going to your Settings.
choose an email that you want to use for all the account.
in to the other accounts that is notusing this
email and add or invite it to your account as the Company Admin.
change the email and user ID for the other two QBO accounts.