How to Change a Lease agreement with the previous owner

[Pamela Holmes]

I contacted the owner about a property that was advertised as vacant. However, when I went to view the property there was an entire family that had just moved in two days prior to me coming to see the property. I was told the previous owner had signed agreement with the tenant for only $650/month. I was very upset and contemplated backing out of the deal, but the owner (who is a private lender) was willing to do an owner finance deal with me. I saw this as a benefits due to this  gives me the opportunity to earn passive income without the debt showing on my credit. Terms of the loan with the lender/seller:

Sale price: 45,000

15% down at 9.85% amortized over 30 years.

My question is: Can I update the lease agreement the tenant has with the previous owner?