How to add multiple downlink using HTTP(post) to queue

Hi All,
Currently I have added HTTP integration for my application which intern using Request.bin. By using ‘downlink-url’ i’m able to post downlink messages as much as I need but every message is getting “REPLACED” by other one. In the TTN console there is an option to choose “Replace/First/Last” to schedule downlink but which is not happening with HTTP(Post) Requests. Can some body help me here.

Thanks in Advance.

There’s a field for this;

"schedule": "replace", // allowed values: "replace" (default), "first", "last"