If 3 people have their names on a house deed, do one of them have more say so about the property if they live there at this time

In Florida (and elsewhere, generally) each person listed on a deed as a joint tenant has an undivided interest equal to the percentage calculated as based on the total joint temants. In this case it appears that, including your mother's estate, there are four equal owners, and non can sell the house unless all four agree, or unless someone filies an action to divide the property equally; If it cannot be divided, the court will order it sold and the proceeds split between all four tenant-owners.

Unfortunately this is one of the downsides of a parent putting their children on title with them as joint owners. While it sounds good "in concept" since "probate will be avoided," in fact, in situations like yours it will likely be ever more expensive to have the legal work done to force the house to be sold. You should consult with an attorney who can look at the deed and give you further advice. I'm sure that you thought about having your brother "buy you and your sister out" of your interests in the house. However, I would bet that he doesn't have anywhere near the funds to do so. A big problem. You and your sister should chip in together and see an attorney for your options. Good Luck!