One spouse can apply as the principal investor and the other as the E-2 spouse, who is employment-authorized incident to status and may work in the shop or anywhere else. Both could apply as investors if each meets the requirements, but that is rarely necessary.
One principal, one authorized spouse
Hypothetical example: the couple own the shop equally and both intend to work in it, one managing service operations and the other running the front office and accounts. The simplest structure is for one of them to be the principal E-2 investor, with the enterprise's Canadian ownership shown through both their shares, and for the other to hold E-2 status as the spouse. The spouse's employment authorization comes with the status itself, so working in the shop, or for another employer, needs no separate permission; the admission record documents it. Children under 21 are admitted as E-2 dependants and may attend school but may not work in the shop, even informally on weekends. Each child's dependant status ends at 21, at which point they need their own status or must depart.
Hypothetical example: the principal investor's spouse runs an online cello-teaching studio and wants to keep lessons after moving. The couple should decide which spouse will be the principal before submitting the application, then preserve the marriage record and admission records that establish the other's derivative status. The teaching business can be conducted by the E-2 spouse because that status carries work authority, but a dependant child cannot assist with bookings, lessons or paid promotion. The family should also calendar every child's twenty-first birthday and choose a separate status well before it arrives. A shared ownership chart explains treaty nationality and control; it does not itself grant a child permission to work.