Review the actual activities, location and immigration basis before the spouse provides services. A pending E-2 case does not authorize work. Qualifying E spouses may have authorization incident to status with the required evidence, but that should not be assumed before the status exists.
Separate due diligence from operational services
Describe what the spouse would actually do and seek advice about the appropriate lawful basis. Do not use the phrase helping family to avoid the activity analysis. The buyer can seek records through advisers or authorized personnel without assuming the spouse may perform accounting work in the United States.
Derivative status is a consequence of the principal's status, not a plan that can be relied on early. An E-2 spouse is employment-authorized incident to status, which means the authorization exists once the spouse holds that classification — it does not reach backwards to cover services performed while an application is pending, and it is not attached to a visitor. Unmarried children under twenty-one accompany as E-2 dependants and may attend school, but they cannot work in that capacity, and a child who reaches twenty-one stops qualifying as a dependant and needs a route of their own. Each person's own activity, not the family relationship, decides which route applies. Nothing a family member does supplies the principal's own elements either: citizenship and ownership still have to establish treaty nationality for the investor and for the enterprise, the money still has to be committed beyond recall and genuinely at risk in an amount substantial against the cost of the business, the business still has to be operating and more than marginal, and the investor still has to develop and direct it.
Hypothetical example: A document-restoration owner is buying an American conservation studio, and the owner's spouse, a bookkeeper, offers two weeks on site rebuilding the seller's ledgers before closing. Two separate questions sit inside that offer. The first is whether the activity is work in the United States regardless of who pays for it. The second is what status the spouse would hold while doing it, which at that point is not E-2. Buying the reconstruction from a licensed accountant keeps diligence and family status apart, and leaves the spouse's own authorization to arrive later, in the ordinary way.