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Unless you can buy your siblings out, they can force a sale by using a partition action. This will be expensive and attorney's fees will be allocated by the judge. It would be best to cooperate with the sale and take as much money possible from the sale instead of giving it to an attorney.
TREC has assistance for you when you are concerned about the violation of ethical rules. To be sure, I would run this by them. For what it's worth, I like your plan and I think TREC is mostly on the lookout for the unauthorized practice of law violations, and referral fees to unlicensed people - I don't see either here.