Loan Strategy

[Tyler M]

Hello, I hope everyone is doing well. I was trying to help my parents invest in RE and was wondering what the best strategy would be for getting loans and using leverage.
I heard that you can get a maximum of ten loans for each person but the first five you only have to put down 20% but for the next five you may have to put down close to 30% and maybe the interest rates won't be as good.
My mom has a 780 credit score I don't think my dads is as good I think it is about 700. How can they obtain the maximum amount of loans? They have enough money for down payments on about 20 houses combined if each house sells for 75k. Is it important that each person applies separately to get the maximum of 10 loans each or can they apply for each conventional loan together and put both their names on each mortgage and still get 20 loans combined?

Thank you for any info.