REST "dry mode" for PUT or POST

Is there an idiomatic way to achieve this:

I need the PUT / POST of this object. However, before I actually put it in, I need to make some changes to a more volatile system, and if that works, I will continue.

So, I will first ask if PUT / POST is suitable, and then actually does PUT / POST.

I thought just to use the dry run query parameter, but it does not look right.

Update : trying to clarify my problem. The fact is that the first PUT is intended only for checking the object.

Me           System A       Volatile System X
|    Dry PUT    |                    :
|-------------->|                    :
|               |                    :
|   20x / 40x   |                    :
|<--------------|                    :
|               :                    :
| Upon PUT OK do some related work   :
|----------------------------------->|
|               :                    |
| Work completely                    |
|<-----------------------------------|
|               :
|PUT (for real) :
|-------------->|
|               |
|     20x       |
|<--------------|