It can be risky to mix friendship and business and if it would be a shame to burn bridges if something unexpected happens and feelings are hurt.

Day of purchase (after the walkthrough), tenants left unexpectedly and trashed the unit.

Since this popped up rather unexpectedly I haven't spoken to a Realtor and I know the seller is not using one.

This was very unexpected for me as the current tenant informed me about her situation very last minute and after the fact.

I doubt any replacement builder would commit to timeframes as there's a lot of variables and several unexpected product shortages.

Long story short, we purchased a house this year for a family member to live in, but they passed away unexpectedly before they could move in.

My main fear is expanding too quickly and if I have a vacancy or something unexpected with one of the properties I don't want to be sitting on multiple mortgages I can't pay.

As long as you have access to a lot of capital to fund renovations, vacancy, and unexpected items, not to mention can handle the stress,  and trust me--t will be a lot, and it's a lot of stuff no one  (except BP!)

Keep cash on hand and hide it somewhere safe for all of the unexpected issues coming your way. 

If they are late, talk to them-- maybe they had unexpected medical bills, maybe a funeral, maybe a car accident/problems?