Each of you can seek E-2 as a treaty investor if each develops and directs the enterprise, and the spouses and unmarried children under twenty-one of each may accompany as E-2 dependants. E-2 spouses are employment-authorized incident to status; children may study but not work.
Give each investor a defined role and each family its own file
Two equal owners can both qualify, but the file must show that each develops and directs rather than one being a passive co-owner. The operating agreement should allocate authority, for example one sibling over estimating and field operations and the other over finance and administration, with both signing on major decisions. Each sibling's consular application then stands on their own share of the investment and their own role.
The spouses, once admitted as E-2 dependants, are employment-authorized incident to status and can work for the roofing company or elsewhere, which matters for a family where one spouse is a bookkeeper or estimator. Children may attend school and must not be put on the payroll, even for summer work, while in dependent status. Because E-2 has no direct path to permanent residence, a family with a child of seventeen should think now about what that child's status will be at twenty-one; a student visa or an employment route of their own may be needed by then.