You are going to have to take the matter to court in Guyana as the US courts cannot enforce any orders over there.
Only the Guyana courts can force her to do what the orders say. Also the US judgement and agreement may not be valid in Guyana and you will have to have the court over there make orders similar to the US and then enforce the orders they make.
If you withhold alimony and you are both in the US she can argue you are in breach and seek compensation.
I would suggest you take it back to court and seek to have the almond suspended for a period that is equal to the value of the items in Guyana and force your ex to eighteen sell them or give them to you and then you start paying the alimony. It is best you have a court order to stop on solid grounds than take it on your self and find yourself in court being sued for non compliance.
I hope this makes sense and is of assistance. If there is nothing further
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