It is possible to sell a share in a family home where the other shares are held by family members, but the sale can be restricted by the type of property, the way in which the shared property was created (for example whether it was a will or a trust), the practical implications as to use of the property, any bonds over the property and the entity the property may be held in.
Assuming it is a normal residential property where the shares are held in all the siblings’ individual names, you could sign an offer to purchase, selling your share to a buyer for a specified price. Conveyancers would then record the share in the new part-owner’s name on the title deed.
The only concern form there onwards would be how the new owner would fit in with the other family property shareholders. If it is leased to a third party, it could well just be an investment set up for the new part-owner. If it is used as a residence for the other family members, it could create an awkward living arrangement that a buyer might not wish to take on.
As individual circumstances may vary, it is a very good idea to consult an attorney for professional advice about your specific situation.