Is it possible to change Flow item using an Exit or Entry trigger?

[alec_hubbardGQLY4]

Hey there, I am trying to use a combiner to combine two halves on an object. Since these are halves, the dimensions change and it is not possible to make a new item Shape Frame. I'd like to try and write a script that exchanges input one's flow item on the combiner for another flow item so that this dimensional change is accurately reflected. 

I am fairly new to this software so am pretty unaware of how to do this or write a script for it. 
Any/all help is greatly appreciated!

Thanks

[joerg_vogel_HsH]

It is probably better to keep both items and exchange shapes to reflect a desired outcome. You can set object size, rotation and location and also shape three properties independently, too. Shapes triple properties begin their name with “offset”. 

Instead of using a combiner you can do this also in a processor or even a queue, if you like. Combining is just putting a second item into a first item by move object command or process flow activity.