I'm planning to buy a condo. My credit rating is 800, my wife's is 690. Buy mortgage only in my name?

Supposedly when two people purchase a property, mortgage rates/fees are based on lowest credit score between both people. First, is this true? Second, if it is, since my credit score is 800, my wife's is 690 can I apply for a condo mortgage only for myself--assuming my income is enough to secure mortgage--and then later add my wife legally as co-owner?

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