You're going to have to figure out if you have an application or not first. If you don't then, you can't pull credit on anyone without written permission. Considering the documentation that has been provided, I am going to assume you do have an application. I'm also going to ignore you stating that only individuals borrowers are covered by joint intent (that is not accurate).
Assuming you have an application (which you need to have an internal definition for if you want to comply with FCRA and ECOA even if you don't have written applications), here is some commentary that may or may not still be relevant as it predates the switch of rulemaking over to CFPB. I do not know Wisconsin law or the "product, terms etc." well enough to know whether you can pull credit on the spouse here.
5. Information on an Applicant's Spouse
A. Permissible purpose. A creditor may request any information concerning an applicant's spouse if that spouse will be permitted to use the account or will be contractually liable upon the account, or the applicant is relying on the spouse's income as a basis for repayment of the credit requested. A creditor may request any information concerning an applicant's spouse if (1) the state law doctrine of necessaries applies to the transaction, or (2) the applicant resides in a community property state, or (3) the property upon which the applicant is relying as a basis for repayment of the credit requested is located in such a state, or (4) the applicant is acting as the agent of the nonapplicant spouse.
B. Lack of permissible purpose. If the creditor receives information clearly indicating that the applicant is not acting as the agent of the nonapplicant spouse, and that the applicant is relying only on separate property to repay the credit extended, and that the state law doctrine of necessaries does not apply to the transaction and that the applicant does not reside in a community property state, the creditor does not have a permissible purpose for obtaining a report on a nonapplicant spouse. A permissible purpose for making a consumer report on a nonapplicant spouse can never exist under the FCRA, where Regulation B, issued under the Equal Credit Opportunity Act (12 CFR 202), prohibits the creditor from requesting information on such spouse. There is no permissible purpose to obtain a consumer report on a nonapplicant former spouse or on a nonapplicant spouse who has legally separated or otherwise indicated an intent to legally disassociate with the marriage. (This does not preclude reporting a prior joint credit account of former spouses for which the spouse that is the subject of the report is still contractually liable. See discussion in section 607, items 3--D infra.)https://www.fdic.gov/regulations/laws/rules/6500-2700.html
Here's a good but dated reference for FCRA (https://www.ftc.gov/sites/default/f...ary-interpretations/110720fcrareport.pdf