No. Corporate ownership evidence and dependent relationship evidence serve different purposes. An eligible spouse seeking L-2 still needs the appropriate family and status documents, even when both spouses own the businesses.
Distinguish two relationships
The companies must establish qualifying affiliation; the spouse must establish the qualifying marriage and dependent procedure. Once in qualifying L-2 status, the spouse may work incident to status with appropriate documentation. Unmarried children under 21 may qualify as dependents but cannot work under L-2.
A shareholder agreement should not be treated as evidence that any family member has permission to enter or work in the United States. Keep the two evidence sets in separate bundles, because they prove different things. Hypothetical example: spouses jointly own both the Canadian and U.S.
businesses and assume the corporate records also serve the dependent application. They do not. The corporate bundle establishes affiliation through ownership and control.
The dependent bundle establishes the qualifying marriage and the spouse own status, through the marriage certificate and the spouse own admission and status documents. Neither can do the other work. Eligible spouses in valid L-2 status are generally work authorized incident to status, and unmarried children under 21 may hold L-2 and attend school but cannot work; company ownership by either spouse changes none of that.
Prepare both bundles at the same time so a gap in one is discovered before it delays the other.