HELP: Seller doesnt know Sq Ft of home

[Krystalyn Jackson]

How do you find the Sq Ft of an off market home if seller is unsure and the sq ft on county records are from before an addition was added and which was before current sellers moved in back in 2013. Homeowner said its a 3bed 2bath but everywhere including public records say 1bed 1bath and 984sq ft. I am assuming the 984sq ft is before the addition but I could be wrong. I tried looking up the survey or appraisal documents but no luck. How do I find out their title company to call? Or what would be my next step? I am in Dallas, Texas and endgame is to wholesale it if that helps. Thanks in advance!!