Can creditors make claim on the will first?
It is not really a matter of jeopardizing their Will, but creditors have a right to be paid from the assets of an estate before the remaining assets are distributed to the beneficiaries named in the Will. As executor it would be your duty to see that their debts are paid from their assets before the distribution of the assets to the beneficiaries. In regard to the house, creditors could force a sale of the property unless other arrangements were made to satisfy the debt. At any such sale, the balance left of the sale over and above the amount owed to creditors and the cost of the sale would go to the beneficiaries of the Will. Generally, this is not required, however, as other arrangements can be made, such as the taking out of a equity loan secured by the property to pay the debt.
Your parent should consider putting the house in a trust for you not just the will. This should saveguard the house