10 siblings inherited 54 acre as of land in Louisiana, eight siblings wants to sell their share of land, one brother is dementia and the other brother trying to stop us from selling. We all live in differ states. What can do?

"eight siblings wants to sell their share of land". How has the land been divided? The best thing would be to sell your share to the person who wants to keep the land.

While Louisiana law is very different from the norm in some ways (mainly regarding inheritance, I think), it is probably similar to Common Law states regarding partition actions. The eight siblings would sue the other two (and a guardian would be appointed for the demented one), and the court would decide how to precede. The property would either be sold or divided into shares.

Why is the other brother trying to stop the sale? Is he in a position to buy out the 9 others? That could solve the problem.

Assuming that the 1 brother can't afford to buy out the others, then it would be easiest for the 8 to hire a lawyer local to the land to handle the court petition to force the sale and arrange the POA or whatever is needed for the brother who can't make decisions. If the 1 brother is smart, he will recognize that he can't stop this and might as well agree.

You could save some or all of a lawyer's fee by contacting the local probate court and seeing what you can do my mail. You can also contact one or more real estate brokers, as long as they know you can't put it up for sale yet. Since it sounds like none of you have seen the land lately, the agents can traipse around the property to see what's what, and look for squatters, neighbor encroachment, dumping, and timber thieves.

(There's no reason why the brother who wants to keep it can't find someone to help buy the rest of you out.)