A joint account requires a clear explanation of ownership, possession and control of the money being invested. Marriage alone does not explain whose assets generated the funds or how the principal investor obtained authority over them.
Document funds and status separately
Review the account history and any transfers between spouses according to the actual arrangement. Separately, spouses and unmarried children under 21 may seek E-2 dependent status. A spouse in valid E-2 or E-2S status is generally work authorized incident to status; children are not.
Family eligibility does not resolve the source-of-funds evidence or the enterprise’s ownership requirements. A jointly held account raises a question about whose funds are being invested, and that question should be answered before the money moves rather than afterwards. Establish how the account is held, who contributed to it and over what period, and whether the intention is that the investor is investing their own share, that the spouse is contributing part, or that a gift is being made.
Each has different documentary requirements and they are not interchangeable. Document the arrangement as what it actually is. Keep this separate from the family's status questions, which turn on the relationship to the principal rather than on the funding.
Any employment authorization available to a spouse depends on holding and maintaining valid dependent status; children may accompany as dependants while unmarried and under 21 without work authorization in that status.