Art. 1406.  Sale to coheir of immovable rights only, rescission for lesion.

In order that the purchaser be not liable to this action, it is besides necessary that the vendor should have ceded to him all his successive rights, that is, all the rights he had in the succession.  If he has only sold his part in the immovables to be divided, this sale shall be subject to rescission for lesion beyond a fourth.