Many of appliances sold in Thailand require a ground and come with CEE 7/7 plug style. CEE 7/7 plug has an whole where you are to insert a ground post. I picked up a few of these ground posts inserts when I was last in Phuket and I need more but can not find them in Isaan. Can anyone direct me where to find the optional ground post inserts for CEE 7/7 plugs.

I have never seen them for sale anywhere. But HomePro and other places do sell a slip over adapter (white plastic with ground pin) that is used to provide ground. The only problem is that only one can fit the normal duplex outlet here. I change plugs to US style for that reason. There is also a new three pin plug for Thailand but have not seen any for sale (they are used in some appliances sold here now).

There is also a new three pin plug for Thailand but have not seen any for sale (they are used in some appliances sold here now).

I had to buy a new microwave oven today, and I was surprised to see all of them have plugs with three round pins like the attached pic. Is that the "new three pin plug for Thailand?"

Yes!

It's a TIS166-2549 (2006) plug.

Supposed to be the replacement for the Schuko plug since 2008.

For our OP, you can't just shove a pin in the hole in your Schuko plug, it won't line up with the outlet. That said, it's fairly close, if you don't mind wrecking the outlet it will provide a ground, at least until someone plugs in the correct plug.