In the US the number of distinct accounts that can be housed under the Family Advisor or Non-Professional Advisor structure is 15. However, if an advisor has 15 distinct clients but one of those clients has two accounts (for example) then the limit can be expanded because there are still only 15 clients.
If an advisor would like the limit expanded due to one of his or her client's having more than one account, then the advisor would have to contact the financial advisors group by creating a ticket. Requests to expand the limit are reviewed by compliance and are not guaranteed.