Hi Fabien, the regular Offset command binds UI controls directly to the offset factory. In your case since you want to do something other than just generate an offset that won't work for your case. So I'm not really sure about modifying the existing command for what you want.

I've attached a command written from scratch that I think does the basics of what you are describing, I hope it is a good starting point for you. Probably requires MoI v4.

- Michael