Some of the repairs were very silly:-A strip of wood on the exterior laundry door isn't painted and she says it needs to be fixed-The fridge ice maker doesn't work and she was told this when she inspected and now 6 months later she's demanding it produce ice-They have mice and want me to exterminate although it's a SFRI provided 48 hours written notice we would be attending to repairs.I arrived at the appointment time with 2 contractors to get everything done.

Explain to him how you arrived at your offer.  

When you finally arrive find that there is something you could do, whatever it is, take action.

Yes the 4 children who want to sell can.In Oklahoma any of the owners may file a Petition with the Court asking that the property be "Partitioned."

That market and your education arrive on the scene just about as important.  

@Marco Petit-BienIn my area there are quite a few companies doing the same thing - representing investors to bid on foreclosure auctions.

In NY it's typically once they are late you give them a 3 day notice to cure and then you serve them with a notice of petition and a petition.

Old check arrived in the mail postmarked the 11th...

How did you arrive at a 10% cap rate? 

In that idea, you may be able to petition the court to rule on what is equitable (read as fair) in terms of the right of redemption held by the sons.