All class 1 legal heirs will have equal right on the property. Any of the legal heir can sell three share of the property to a third party, provided their share is defined by proper documentation. One legal heir cannot impose terms upon the other, if they are not agreeable to it. If both the parties agree upon same terms, sale can happen.
If you think the other's terms are unreasonable, and if the property is not divisible, file a Suit for partition. If the court finds that the property is not divisible, or upon the request of parties, Court can have the property sold, and the proceeds will be shared by all the parties.
Injunction (Temporary) is any relief granted by the Court pending the hearing and final disposal of the Suit, "... restraining a person from beginning or continuing an action threatening or invading the legal right of another, or compelling a person to carry out a certain act". It is unlikely that the occupier will be forced to vacate the property till the matter is pending, and he still has rights over the property, unless he is causing damage to the property. But the court can allow the other legal heirs to occupy the property too, upon application, during the pendency of the Suit.