With regards to your question about return request
I have no access to cancel the return request, you can email the buyer to cancel the return request if the buyer did not buy another item as birthday party gift. If the buyer states that his child birthday party has passed and shows that he still wants to return the item, because he buys the item in the store instead. Then he can refuse to receive the item, what you need to do is to approval request. If the buyer did not have a reply, what you can do is to approval request or close request in 48 hours.