No automatic immigration conclusion follows. Establish the actual principal, ownership and contribution, and assess the other spouse’s intended role separately.
Separate debt liability from family status
A qualifying spouse and unmarried children under 21 may seek derivative status subject to individual requirements and applicable age rules. Signing a loan does not itself establish derivative residence or make two people interchangeable as the principal investor. Two questions are frequently merged and should be answered separately: who is the investor, and who is coming.
The investor is identified by ownership of the capital and by participation in the enterprise, evidenced by the subscription documents and the enterprise's own records. Family members are identified by their relationship, evidenced by civil-status documents, and a spouse and unmarried children under twenty-one may generally be included as derivatives on that basis. A joint loan makes two people liable to a lender and says nothing about which of them holds the investment.
Settle the point early, because the answer shapes every document that follows and is awkward to revise later. Hypothetical example: two spouses, one of them an engineer, sign the same facility and assume either may be named as the investor, and the subscription documents settle the question in one direction only.