You state the your parent's farm is now deeded in five siblings names, that one sibling lives on the farm as invited to by your parents, and that this sister
is now making changes that are not approved by the four other siblings and your dad. [I do not know if your mother does approve of the changes, or you simply didn't mention her.] You ask, "If it comes to it, can we evict her regardless of our parents' input?' I suggest that this problem should be resolved by negotiation, and mediation if necessary, not by litigation.
First, it is not clear what your rights, if any, to evict the sister are. She is one owner of the property. Normally you can't evict an owner, unless there is a provision in the deed, or a lease, allowing you to do so.
Far more importantly, I think it would unwise to try to evict your sister regardless of your parents' input. While the farm is legally owned by the five siblings, it is morally still owned by your parents. For you, of any of your siblings, to take legal action about the farm and ignore your parents desires regarding your sister seems likely to result in ill will and family bitterness. I propose that you put all your efforts into trying to work this out on the family level.