I'm trying to purchase a property from my daughter creatively for what she owes on the mortgage.

actual mortgage, actual taxes, actual insurance, actual capex.with that said it will probably be closer to the 50% rule than using teeny tiny percentages for vacancy, repairs, capex, etc.

I understand home designs are pretty expensive, and cannot just be applied to any lot/existing neighborhood.

Since the account is linked to your mortgage, overspending can increase mortgage balances instead of paying them down.

Some PM will also pay the mortgage on your behalf or I set it up that I pay the mortgage after I get the remaining rent. 

My wife is a mortgage broker and she is seeing a scary rise in condos that are becoming unwarrantable.

This amounts to lost opportunity because if you had purchased RE, at the closing it can start producing return. 5) ADUs detract from the existing structure whether this is privacy, a garage, or just yard space. 6) this is related to number 1, but there are many more buyers looking to purchase homes for their family than there are RE investors looking to purchase small unit count properties.

My first rental has over 100k equity and the rent is almost double the debt payment (I've got a really great mortgage from 2020 so it cashflows very well).

I'm trying to figure out if I can get the consistency in MTR for the price I need to cover the mortgage. 

We are planning to finance with a second mortgage and will use the property on occasion but would also like to generate an income and/or offset the mortgage.