(oops - I didn't realize there was a category of "initial classification" items and a separate category for those reclassifying residency)
Looks like your best bets are showing the family connections, buying a house, and getting welfare benefits.
My guess is severing as many ties as possible with Texas (selling house, closing local bank accts if any, etc) would further evidence residency in FL.
My state has similar requirements. I have also heard of people retaining an attorney to appeal denials of residency. It could mean big bucks, so sometimes paying an attorney would be worth it. Good luck!