Markets are typically dependent on your strategy...LTR, STR, flips, BRRRRS, etc. 

Depending on the amount of months left on the lease, you could add him and if it doesn’t work out, serve a non-renewal notice.  

However, ultimately, the decision to keep or sell the property depends on your personal preferences and financial goals.Reasons to keep the fourplex:Established cash flow: You mentioned the property will cash flow around $675/month now and $1000/month when paid off in 7 years.

With 3 deals or more you can typically expect 10-15% down depending on the rehab size and complexity.

It all depends on what works best for you.

It depends on your state, filling status, and type of gain passed through.

While rental properties typically offer lower ROI, they provide long-term stability and cash flow, which could act as a cushion if markets fluctuate or your job situation changes.Ultimately, it depends on your investment goals.

Any advice around this attached ADU dynamic would be greatly appreciated, as I keep getting different answers depending on who I call. 

I preferred propstream but it depends also on what your goals are.

It depends on each state.