Yes, and that arrangement should be described accurately. The applicant's L-1A status depends on their own qualifying employment and proposed role; other relatives' continued involvement in the Ontario operation is a separate, legitimate fact to disclose.
Keep each person's role distinct in the file
Identify who remains in Ontario running day-to-day operations and who is transferring, along with each person's actual authority. This avoids the impression that the whole family is collectively described as the transferring employee, and it clarifies which decisions genuinely move with the applicant to the United States.
Separate the corporate transfer analysis from each relative's immigration plan. Identify who owns each entity, who continues managing the Canadian operation, and which authority the beneficiary alone will exercise in America. The principal still must satisfy the qualifying relationship, foreign-employment, and managerial or executive requirements even when relatives share control. A qualifying spouse in L-2 classification receives employment authorization incident to status; do not assume that rule transfers managerial eligibility or company authority to another family member. The common mistake is using collective phrases such as "the family runs both companies," which prevents a reviewer from seeing the individual reporting structure and can contradict the proposed division of duties.
Hypothetical example: A feed manufacturer in the Strathroy-Caradoc area transfers its president while her brother remains responsible for Ontario production and their mother chairs the board. A responsibility matrix shows who approves hiring, pricing, suppliers, and capital purchases on each side. Her husband may work incident to valid L-2 spousal status, but his permission does not make him an executive of the petitioning group; any company role is documented separately and truthfully.