HELP! First time screening tenants

[Patrick M.]

This is my first rental in a B/B+ 4bd/2.5ba area asking 2k rent. 2k deposit.  Pet friendly.  No evictions. No felonies. Owner pays trash, water, utilities. Responsible for mow and snow.

Using mysmartmove to screen.

I've been getting some showings and taking phone calls of interested parties.  So far my first showing the people gave off a weird vibe..they didn't ask for an app and I didn't offer.  Boyfriend and girlfriend just moved to area. She has a kid and he has 3.

2nd party is two sisters and their elderly mom.  Very nice people.  Seemed genuine.  Have been 7 year tenants at their current place but owner is selling.  She's been very upfront and mentioned a bankruptcy a while back.  (didn't specify how long ago).  Emailed her an app.  And will need to get one from the sister as well.

Another party is boyfriend selling the house nearby.  He has 2 kids.  Girlfriend doesn't have any.  Seemed ok on the phone but gave me the line "we've already applied a few places and they were a little small for us but we've passed all the background checks and credit I just want you to know we're qualified"  I'll still run their information if they take an app but that line gave me a bad vibe.

TLDR: I expected a lot more married couples or individuals to apply.  What is the best way to handle multiple adults with no real legal obligation to each other when screening?  My biggest concern: the combined income they qualify (3x rent) but individually they don't and a breakup means big time problems collecting rent.