I was carrying a contact for the sale of my business, the purchaser has died, his kids went in and changed the locks payments have not been made do I need to give a grace period before I go in and repo?

You are obligated to the exact terms of the contract, no more, no less. So what exactly does the contract for deed of the busienss say what can or will happen if they default.

Also who is the actual owner, Is it still in the estate or has the ownership been decided in probate court . * or did the contract state a heir perhaps.

As for as changing locks, why not, you sold it to them, it is not a rental and they can change locks if they want to.

All of my contract for deeds basically said once they were in default for more than 15 days, the contract changed over to a month to month rental, and you don't even have to do anything but evict.

So hopefully your attorney wrote up a legal and proper contract.

You don't provide enough detail for a good answer to be given. Seattle is very restrictive in these matters and requires more than outside the city. You would be best served calling a local real estate attorney for an hour of their time.

Does your contract provide a grace period? If not then there is none. But you may not be able to just go in and repo. You have to read the contract for what it says about default of the contract.

You will probably have to send them a notice that they are in default of the contract and give them a period (a week or so) to bring the contract up to date. If they don't you will probably have to go to court to get an order for them to vacate.